Summary:
- This diff also restructures the search package in a few ways:
- Rename package to `thread-search` instead of `search-bar`
- Move SearchQuerySubscription and SearchMailboxPerspective inside
package. This allows SearchQuerySubscription to have access to
SearchActions in a clean way and keeps all of the search related code
in 1 package
- Remove SearchMailboxPerspetcive from mailbox-perspective.coffee
- Adds temporary spinner while we get a new design for it
Test Plan: - TODO
Reviewers: evan, bengotow
Reviewed By: bengotow
Differential Revision: https://phab.nylas.com/D2868
