Fix Typescript typings in react-native-flipper (facebook#3209)

Summary:
The implementation of react-native-flipper [makes runtime assertions](https://github.com/facebook/flipper/blob/main/react-native/react-native-flipper/index.js#L20) about some variables but those type requirements [aren't properly reflected in the Typescript type defs](https://github.com/facebook/flipper/blob/main/react-native/react-native-flipper/index.d.ts#L45).

## Changelog

Corrected Typescript type defs in react-native-flipper

Pull Request resolved: facebook#3209

Test Plan:
(No runtime effect)
In vscode, the typings now properly restrict the arguments to `FlipperResponder.success`,  `FlipperResponder.error`, and  `FlipperConnection.send`

Reviewed By: antonk52

Differential Revision: D33307792

Pulled By: mweststrate

fbshipit-source-id: da3bf7fcacdf3718dc9a625e4229f3c8ecd7ac93

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

@@ -41,13 +41,15 @@ declare namespace Flipper {
     runInBackground?(): boolean;
   }
 
+  type Serializable = undefined | Array<any> | object
+
   export interface FlipperResponder {
-    success(response?: any): void;
-    error(response: any): void;
+    success(response?: Serializable): void;
+    error(response: Serializable): void;
   }
 
   export interface FlipperConnection {
-    send(method: string, data: any): void;
+    send(method: string, data: Serializable): void;
     reportErrorWithMetadata(reason: string, stackTrace: string): void;
     reportError(error: Error): void;
     receive(