Fix jest mocking in tests (#592)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/592

Finally we can join the 21st century and use `jest.mock` in tests!

I'm enabling the ts-jest transform to `*/__tests__/*.tsx` files. This takes care of transforming the typescript, and preserves jest mock capabilities.
I have left the existing custom transform on all other files, so they will continue to work as usual.

Caveats:
* Our existing custom transforms will no longer be applied in tests.
  * With our current suite this makes no difference. But bear in mind things like importing directly from 'flipper' instead of the actual files, won't work. However, I don't see this being a problem, as I think they'll only be needed inside the actual product code.

Reviewed By: passy

Differential Revision: D17978753

fbshipit-source-id: df7b312b5dd5592e4aa4f8df605f5952ea3158e9

src/chrome/__tests__/PluginInstaller.node.tsx

@@ -7,11 +7,17 @@
  * @format
  */
 
+jest.mock('../../fb-stubs/Logger');
+try {
+  jest.mock('../../fb/Logger');
+} catch {
+  // Allowed to fail when fb modules are not present.
+}
+
 import {default as PluginInstaller, PluginDefinition} from '../PluginInstaller';
 
 import React from 'react';
 import {render, waitForElement} from '@testing-library/react';
-import {init as initLogger} from '../../fb-stubs/Logger';
 import configureStore from 'redux-mock-store';
 
 const mockStore = configureStore([])({application: {sessionId: 'mysession'}});
@@ -31,7 +37,6 @@ const indexMock: algoliasearch.Index = ({
 
 beforeEach(() => {
   indexMock.search = jest.fn(async () => SEARCH_RESULTS);
-  initLogger(mockStore as any, {isTest: true});
 });
 
 test('load PluginInstaller list', async () => {