Install plugin from package file

Summary:
Adding a way to install plugins directly from package files. This is required for testing after packaging format changes.

Stage 1: refactored the plugin manager component file layout,  no functional changes.

Reviewed By: jknoxville

Differential Revision: D19741085

fbshipit-source-id: bd9d72382ddc4894de5b3cd9a71877c799886fbf

src/dispatcher/__tests__/plugins.node.js

@@ -34,7 +34,6 @@ test('dispatcher dispatches REGISTER_PLUGINS', () => {
 test('getDynamicPlugins returns empty array on errors', () => {
   ipcRenderer.sendSync = jest.fn();
   ipcRenderer.sendSync.mockImplementation(() => {
-    console.log('aaa');
     throw new Error('ooops');
   });
   const res = getDynamicPlugins();