:warn: Fakeclient: Add apply support

This change adds apply support into the fake client.

This relies on the upstream support for this which is implemented in a
new [FieldManagedObjectTracker][0]. In order to support many types, a
custom `multiTypeConverter` is added.

[0]: https://github.com/kubernetes/kubernetes/blob/4dc7a48ac6fb631a84e1974772bf7b8fd0bb9c59/staging/src/k8s.io/client-go/testing/fixture.go#L643

Author: alvaroaleman

go.mod

@@ -32,6 +32,8 @@ require (
 	sigs.k8s.io/yaml v1.4.0
 )
 
+require sigs.k8s.io/structured-merge-diff/v4 v4.7.0
+
 require (
 	cel.dev/expr v0.23.1 // indirect
 	github.com/antlr4-go/antlr/v4 v4.13.0 // indirect
@@ -96,7 +98,6 @@ require (
 	sigs.k8s.io/apiserver-network-proxy/konnectivity-client v0.31.2 // indirect
 	sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect
 	sigs.k8s.io/randfill v1.0.0 // indirect
-	sigs.k8s.io/structured-merge-diff/v4 v4.7.0 // indirect
 )
 
 replace k8s.io/client-go => k8s.io/client-go v0.0.0-20250603014204-647bbbe85970