improve "not a registered callable module" error message (#28913)

Summary:
Motivation:

`Invariant Violation: Module AppRegistry is not a registered callable module (calling runApplication).` is an error that happens rarely, and most SO answers end up recommending to use `react-native bundle` to work around. I stumbled upon this error the other day and it took me a while to figure out that the error was caused by the fact that my `entryFile` path was pointing to an existing but invalid file. I figured it would be nice to mention this because I believe this will be a frequent cause of the error.

## Changelog

<!-- Help reviewers and the release process by writing your own changelog entry. For an example, see:
https://github.com/facebook/react-native/wiki/Changelog
-->

[General] [Changed] - improve "not a registered callable module error message"

Pull Request resolved: #28913

Test Plan:
tested locally with RNTester, prints

```
[Sun May 17 2020 18:15:55.396]  ERROR    Invariant Violation: Module AppRegistry is not a registered callable module (calling runApplication). This can happen when the application entry file path is incorrect.
      On Android, verify 'getJSMainModuleName()' in 'MainApplication.java' and 'project.ext.react.entryFile' in 'android/app/build.gradle'.
      On iOS, verify '- (NSURL *)sourceURLForBridge:(RCTBridge *)bridge' in 'AppDelegate.m' and 'ENTRY_FILE' env. variable passed to 'react-native-xcode.sh' (if any) in 'Build Phases' -> 'Bundle React Native code and images'.
```

in metro logs

Reviewed By: mdvacca

Differential Revision: D23107228

Pulled By: fkgozali

fbshipit-source-id: 0712ed7e593ba96b041578bafdbefcd09a3994b7

Libraries/BatchedBridge/MessageQueue.js

@@ -404,15 +404,12 @@ class MessageQueue {
     const moduleMethods = this.getCallableModule(module);
     invariant(
       !!moduleMethods,
-      'Module %s is not a registered callable module (calling %s)',
-      module,
-      method,
+      `Module ${module} is not a registered callable module (calling ${method}). A frequent cause of the error is that the application entry file path is incorrect. 
+      This can also happen when the JS bundle is corrupt or there is an early initialization error when loading React Native.`,
     );
     invariant(
       !!moduleMethods[method],
-      'Method %s does not exist on module %s',
-      method,
-      module,
+      `Method ${method} does not exist on module ${module}`,
     );
     moduleMethods[method].apply(moduleMethods, args);
     Systrace.endEvent();

Libraries/BatchedBridge/__tests__/MessageQueue-test.js

@@ -108,7 +108,8 @@ describe('MessageQueue', function() {
     const unknownModule = 'UnknownModule',
       unknownMethod = 'UnknownMethod';
     expect(() => queue.__callFunction(unknownModule, unknownMethod)).toThrow(
-      `Module ${unknownModule} is not a registered callable module (calling ${unknownMethod})`,
+      `Module ${unknownModule} is not a registered callable module (calling ${unknownMethod}). A frequent cause of the error is that the application entry file path is incorrect. 
+      This can also happen when the JS bundle is corrupt or there is an early initialization error when loading React Native.`,
     );
   });