Changing interface of UIManagerProvider to be a functional interface …

…for the return type of getUIManagerProvider()

Summary:
Changing interface of UIManagerProvider to be a [functional(SAM) interface](https://kotlinlang.org/docs/fun-interfaces.html) for the return type of getUIManagerProvider() to be used in various apps for clarity.

Changelog:
[Internal] internal

Reviewed By: javache

Differential Revision: D50846818

fbshipit-source-id: c22977b45b0118d70b994e14ff79ea8990248e3c

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridge/UIManagerProvider.kt

@@ -15,7 +15,7 @@ import com.facebook.react.common.annotations.DeprecatedInNewArchitecture
  * in isolation of others part of the new architecture of React Native.
  */
 @DeprecatedInNewArchitecture
-interface UIManagerProvider {
+fun interface UIManagerProvider {
 
   /* Provides a {@link com.facebook.react.bridge.UIManager} for the context received as a parameter. */
   fun createUIManager(context: ReactApplicationContext): UIManager