Fix sprite picking viewport (#19747)

# Objective

Fixes sprite picking when using a viewport. Related to #19744.

## Solution

- Do not substract `viewport.min` as `Camera::viewport_to_world` already
does that.
- Skip pointers outside the viewport.

## Testing

Tested with the following example:

<details>
<summary>Click to expand code</summary>

```rust
use bevy::{
    prelude::*, render::camera::Viewport, window::SystemCursorIcon, winit::cursor::CursorIcon,
};

fn main() -> AppExit {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .insert_resource(ClearColor(Color::BLACK))
        .run()
}

fn setup(mut commands: Commands, window: Single<&Window>) {
    commands.spawn((
        Camera2d,
        Camera {
            clear_color: ClearColorConfig::Custom(Color::WHITE),
            viewport: Some(Viewport {
                physical_position: UVec2::new(
                    window.physical_width() / 4,
                    window.physical_height() / 4,
                ),
                physical_size: UVec2::new(
                    window.physical_width() / 2,
                    window.physical_height() / 2,
                ),
                ..default()
            }),
            ..default()
        },
    ));

    commands
        .spawn((
            Transform::from_xyz(100.0, 100.0, 0.0),
            Sprite::from_color(Color::srgb(0.0, 1.0, 0.0), Vec2::new(200.0, 200.0)),
            Pickable::default(),
        ))
        .observe(
            |trigger: On<Pointer<Drag>>, mut transform: Query<&mut Transform>| {
                let mut transform = transform.get_mut(trigger.target()).unwrap();
                transform.translation.x += trigger.delta.x;
                transform.translation.y -= trigger.delta.y;
            },
        )
        .observe(
            |_: On<Pointer<DragStart>>,
             window: Single<Entity, With<Window>>,
             mut commands: Commands| {
                commands
                    .entity(*window)
                    .insert(CursorIcon::from(SystemCursorIcon::Grabbing));
            },
        )
        .observe(
            |_: On<Pointer<DragEnd>>,
             window: Single<Entity, With<Window>>,
             mut commands: Commands| {
                commands.entity(*window).remove::<CursorIcon>();
            },
        );
}
```
</details>

Author: jannik4

crates/bevy_sprite/src/picking_backend.rs

@@ -145,13 +145,15 @@ fn sprite_picking(
             continue;
         };
 
-        let viewport_pos = camera
-            .logical_viewport_rect()
-            .map(|v| v.min)
-            .unwrap_or_default();
-        let pos_in_viewport = location.position - viewport_pos;
+        let viewport_pos = location.position;
+        if let Some(viewport) = camera.logical_viewport_rect() {
+            if !viewport.contains(viewport_pos) {
+                // The pointer is outside the viewport, skip it
+                continue;
+            }
+        }
 
-        let Ok(cursor_ray_world) = camera.viewport_to_world(cam_transform, pos_in_viewport) else {
+        let Ok(cursor_ray_world) = camera.viewport_to_world(cam_transform, viewport_pos) else {
             continue;
         };
         let cursor_ray_len = cam_ortho.far - cam_ortho.near;