Refactor builder extension APIs and update dependencies (#4113)

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**What kind of change does this PR introduce?**
<!-- Bug fix, feature, docs update, ... -->

Update

**What is the new behavior?**
<!-- If this is a feature change -->

Changed builder extension methods to use IReactiveUIBuilder interface
for improved flexibility and consistency across platforms. Added
System.Reactive package references to multiple projects.

Updated Splat and Microsoft.Reactive.Testing package versions. 

Improved code analysis attributes and suppressions for better trimming
and AOT compatibility.

Updated API approval files to reflect public API changes.


**What might this PR break?**

Un-released version

**Please check if the PR fulfills these requirements**
- [x] Tests for the changes have been added (for bug fixes / features)
- [ ] Docs have been added / updated (for bug fixes / features)

**Other information**:

Author: ChrisPulman

src/Directory.Packages.props

@@ -4,7 +4,7 @@
     <CentralPackageTransitivePinningEnabled>true</CentralPackageTransitivePinningEnabled>
   </PropertyGroup>
   <PropertyGroup>
-    <SplatVersion>16.0.1</SplatVersion>
+    <SplatVersion>16.1.1</SplatVersion>
     <XamarinAndroidXCoreVersion>1.13.1.4</XamarinAndroidXCoreVersion>
     <XamarinAndroidXLifecycleLiveDataVersion>2.8.4.1</XamarinAndroidXLifecycleLiveDataVersion>
   </PropertyGroup>
@@ -16,7 +16,8 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="3.11.0" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.14.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
-    <PackageVersion Include="Microsoft.Reactive.Testing" Version="6.0.1" />
+    <PackageVersion Include="Microsoft.Reactive.Testing" Version="6.0.2" />
+    <PackageVersion Include="System.Reactive" Version="6.0.2" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Microsoft.Windows.SDK.BuildTools" Version="10.0.26100.4948" />
     <PackageVersion Include="Microsoft.Xaml.Behaviors.Wpf" Version="1.1.135" />

src/ReactiveUI.AndroidX/Builder/AndroidXReactiveUIBuilderExtensions.cs

@@ -25,7 +25,7 @@ public static class AndroidXReactiveUIBuilderExtensions
     /// </summary>
     /// <param name="builder">The builder instance.</param>
     /// <returns>The builder instance for chaining.</returns>
-    public static ReactiveUIBuilder WithAndroidX(this ReactiveUIBuilder builder)
+    public static IReactiveUIBuilder WithAndroidX(this IReactiveUIBuilder builder)
     {
         if (builder is null)
         {
@@ -42,7 +42,7 @@ public static ReactiveUIBuilder WithAndroidX(this ReactiveUIBuilder builder)
     /// </summary>
     /// <param name="builder">The builder.</param>
     /// <returns>The builder instance for chaining.</returns>
-    public static ReactiveUIBuilder WithAndroidXScheduler(this ReactiveUIBuilder builder)
+    public static IReactiveUIBuilder WithAndroidXScheduler(this IReactiveUIBuilder builder)
     {
         if (builder is null)
         {

src/ReactiveUI.AndroidX/ReactiveUI.AndroidX.csproj

@@ -12,6 +12,7 @@
     <PackageReference Include="Xamarin.AndroidX.Legacy.Support.Core.UI" />
     <PackageReference Include="Xamarin.Google.Android.Material" />
     <PackageReference Include="Xamarin.AndroidX.Lifecycle.LiveData" />
+    <PackageReference Include="System.Reactive" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\ReactiveUI\ReactiveUI.csproj" />

src/ReactiveUI.AndroidX/Registrations.cs

@@ -14,12 +14,6 @@ namespace ReactiveUI.AndroidX;
 public class Registrations : IWantsToRegisterStuff
 {
     /// <inheritdoc/>
-#if NET6_0_OR_GREATER
-    [RequiresDynamicCode("Register uses methods that require dynamic code generation")]
-    [RequiresUnreferencedCode("Register uses methods that may require unreferenced code")]
-    [SuppressMessage("Trimming", "IL2046:'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides.", Justification = "Not all paths use reflection")]
-    [SuppressMessage("AOT", "IL3051:'RequiresDynamicCodeAttribute' annotations must match across all interface implementations or overrides.", Justification = "Not all paths use reflection")]
-#endif
     public void Register(Action<Func<object>, Type> registerFunction)
     {
 #if NET6_0_OR_GREATER

src/ReactiveUI.Blazor/Builder/BlazorReactiveUIBuilderExtensions.cs

@@ -23,7 +23,7 @@ public static class BlazorReactiveUIBuilderExtensions
     /// </summary>
     /// <param name="builder">The builder instance.</param>
     /// <returns>The builder instance for chaining.</returns>
-    public static ReactiveUIBuilder WithBlazor(this ReactiveUIBuilder builder)
+    public static IReactiveUIBuilder WithBlazor(this IReactiveUIBuilder builder)
     {
         if (builder is null)
         {
@@ -40,7 +40,7 @@ public static ReactiveUIBuilder WithBlazor(this ReactiveUIBuilder builder)
     /// </summary>
     /// <param name="builder">The builder.</param>
     /// <returns>The builder instance for chaining.</returns>
-    public static ReactiveUIBuilder WithBlazorScheduler(this ReactiveUIBuilder builder)
+    public static IReactiveUIBuilder WithBlazorScheduler(this IReactiveUIBuilder builder)
     {
         if (builder is null)
         {

src/ReactiveUI.Blazor/ReactiveUI.Blazor.csproj

@@ -8,6 +8,7 @@
   <ItemGroup>
     <PackageReference Include="Reactive.Wasm" />
     <PackageReference Include="Microsoft.AspNetCore.Components" />
+    <PackageReference Include="System.Reactive" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\ReactiveUI\ReactiveUI.csproj" />

src/ReactiveUI.Blend/ReactiveUI.Blend.csproj

@@ -18,6 +18,7 @@
   <ItemGroup>
     <Compile Include="Platforms\net4\**\*.cs" />
     <PackageReference Include="Microsoft.Xaml.Behaviors.Wpf" />
+    <PackageReference Include="System.Reactive" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\ReactiveUI\ReactiveUI.csproj" />

src/ReactiveUI.Drawing/Builder/ReactiveUIBuilderDrawingExtensions.cs

@@ -15,7 +15,7 @@ public static class ReactiveUIBuilderDrawingExtensions
     /// </summary>
     /// <param name="builder">The builder instance.</param>
     /// <returns>The builder instance for method chaining.</returns>
-    public static ReactiveUIBuilder WithDrawing(this ReactiveUIBuilder builder)
+    public static IReactiveUIBuilder WithDrawing(this IReactiveUIBuilder builder)
     {
         if (builder is null)
         {

src/ReactiveUI.Drawing/ReactiveUI.Drawing.csproj

@@ -24,5 +24,6 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Splat.Drawing" />
+    <PackageReference Include="System.Reactive" />
   </ItemGroup>
 </Project>

src/ReactiveUI.Maui/Builder/MauiReactiveUIBuilderExtensions.cs

@@ -26,7 +26,7 @@ public static class MauiReactiveUIBuilderExtensions
     /// <param name="builder">The builder instance.</param>
     /// <param name="dispatcher">The MAUI dispatcher to use for the main thread scheduler.</param>
     /// <returns>The builder instance for chaining.</returns>
-    public static ReactiveUIBuilder WithMaui(this ReactiveUIBuilder builder, IDispatcher? dispatcher = null)
+    public static IReactiveUIBuilder WithMaui(this IReactiveUIBuilder builder, IDispatcher? dispatcher = null)
     {
         if (builder is null)
         {
@@ -43,7 +43,7 @@ public static ReactiveUIBuilder WithMaui(this ReactiveUIBuilder builder, IDispat
     /// </summary>
     /// <param name="builder">The builder.</param>
     /// <returns>The builder instance for chaining.</returns>
-    public static ReactiveUIBuilder WithMauiScheduler(this ReactiveUIBuilder builder)
+    public static IReactiveUIBuilder WithMauiScheduler(this IReactiveUIBuilder builder)
     {
         if (builder is null)
         {