Remove deprecated UIImplementationProvider

Summary:
UIImplementation(Provider) is not compatible with the new renderer (Fabric) and the relevant constructors have been marked deprecated for a while. While ReactInstanceManagerBuilder creates a default instance, it's not even used by CoreModulesPackage.

Changelog: [Android][Removed] Removed deprecated UIImplementationProvider

Reviewed By: NickGerleman

Differential Revision: D39271916

fbshipit-source-id: 20a3b02843ea9a2ba4bfc1352037239febbafc64

ReactAndroid/src/main/java/com/facebook/react/ReactNativeHost.java

@@ -19,7 +19,6 @@ import com.facebook.react.common.SurfaceDelegate;
 import com.facebook.react.common.SurfaceDelegateFactory;
 import com.facebook.react.devsupport.DevSupportManagerFactory;
 import com.facebook.react.devsupport.interfaces.RedBoxHandler;
-import com.facebook.react.uimanager.UIImplementationProvider;
 import java.util.List;
 
 /**
@@ -77,7 +76,6 @@ public abstract class ReactNativeHost {
             .setLazyViewManagersEnabled(getLazyViewManagersEnabled())
             .setRedBoxHandler(getRedBoxHandler())
             .setJavaScriptExecutorFactory(getJavaScriptExecutorFactory())
-            .setUIImplementationProvider(getUIImplementationProvider())
             .setJSIModulesPackage(getJSIModulePackage())
             .setInitialLifecycleState(LifecycleState.BEFORE_CREATE)
             .setReactPackageTurboModuleManagerDelegateBuilder(
@@ -117,16 +115,6 @@ public abstract class ReactNativeHost {
     return mApplication;
   }
 
-  /**
-   * Get the {@link UIImplementationProvider} to use. Override this method if you want to use a
-   * custom UI implementation.
-   *
-   * <p>Note: this is very advanced functionality, in 99% of cases you don't need to override this.
-   */
-  protected UIImplementationProvider getUIImplementationProvider() {
-    return new UIImplementationProvider();
-  }
-
   protected @Nullable JSIModulePackage getJSIModulePackage() {
     return null;
   }