✨ 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

@@ -29,6 +29,7 @@ require (
 	k8s.io/client-go v0.34.0-alpha.2
 	k8s.io/klog/v2 v2.130.1
 	k8s.io/utils v0.0.0-20250604170112-4c0f3b243397
+	sigs.k8s.io/structured-merge-diff/v4 v4.7.0
 	sigs.k8s.io/yaml v1.4.0
 )
 
@@ -97,5 +98,4 @@ 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
 )