Summary:
Flipper plugins fail when importing css from third-party dependencies. This diff tries to fix that.
Effectively, the plugin can import the css and export it when is bundled.
When we load the plugin, we check if there's a css file for it. If there's one, we return it and try to use it.
Reviewed By: aigoncharov
Differential Revision: D40758178
fbshipit-source-id: e53afffcc481504905d5eeb1aea1f9114ee2a86b