Summary:
- Adds button inside the message list to print the thread
- Adds cmdctrl-p binding to print thread
- Adds new action and new internal_package to listen to this action.
- Creates a standalone browser window with current thread html, and removes all
collapsed messsages from the print view
Test Plan: - Manual
Reviewers: evan, bengotow
Reviewed By: bengotow
Differential Revision: https://phab.nylas.com/D2310
