Summary:
- Add a close button when hovering over the component
- Remove the route corresponding to it when clicking on closing
Note:
- This is a part of this PR: https://github.com/facebook/flipper/pull/488
Reviewed By: mweststrate
Differential Revision: D20444419
fbshipit-source-id: 5ebe112c542b033a3e10ed10f23d6a04a730c657