Make sure callbacks are not reused and reloading works

Summary:
This diff is part of the bigger task T60496135

This diff changes the RN support from crude to decent citizen, making sure we don't recycle callbacks over the bridge, use subscriptions were possible, and making sure connecting, disconnecting, etc works correctly

For example, connect and disconnect hooks should work.

Finally, throw in hot reloading into the mix, which causes the registerPlugin to be triggered another time, without the old one every been unloaded.
This should trigger a new 'onConnect' on the client, to make sure it can restore any state / subscriptions necessary, even though the never disappeared in the Java world.

These cases should all be handled well.

Reviewed By: jknoxville

Differential Revision: D19347330

fbshipit-source-id: de64a08f4043f01528c794430ccc3c717abf0180

react-native/react-native-flipper/index.d.ts

@@ -57,12 +57,13 @@ declare namespace Flipper {
   }
 }
 
+/**
+ * Internal api to connect to the native Java module, not to be used directly
+ */
 declare module 'Flipper' {
   export function registerPlugin(
     pluginId: string,
     runInBackground: boolean,
-    onConnect: () => void,
-    onDisconnect: () => void,
   ): void;
   export function send(pluginId: string, method: string, data: string): void;
   export function reportErrorWithMetadata(
@@ -71,13 +72,13 @@ declare module 'Flipper' {
     stackTrace: string,
   ): void;
   export function reportError(pluginId: string, error: string): void;
-  export function subscribe(
-    pluginId: string,
-    method: string,
-    listener: (data: string, responderId: number) => void,
-  ): void;
+  export function subscribe(pluginId: string, method: string): void;
   export function respondSuccess(responderId: string, data?: string): void;
   export function respondError(responderId: string, error: string): void;
 }
 
+/**
+ * Register a new plugin
+ * @param plugin
+ */
 export function addPlugin(plugin: Flipper.FlipperPlugin): void;