Summary:
- New behavior is that the in split mode, you will perform actions on
the selection via the MessageListToolbar (the toolbar positioned above
the message list)
- Refactored and moved around a bunch of code to achieve this:
- Mostly renaming stuff and moving stuff around and removing some
duplication
- Update naming of toolbar role to a single role, and update relevant code
- Converted and refactored a bunch of code into ES6, specifically to reuse the code for the ThreadActionsToolbar at the 2 locations
- Deprecated MultiselectActionBar in favor of MultiselectToolbar
- Deprecated old roles
- Punted the animation for the stackable cards in the selection display for now.
- #370
Test Plan: - Manual and unit tests
Reviewers: evan, drew, bengotow
Reviewed By: bengotow
Differential Revision: https://phab.nylas.com/D2756
