[web] Link modal in the thread menu
Summary:
The thread menu should allow the user to open up the media gallery.
Linear: https://linear.app/comm/issue/ENG-2879/link-modal-in-the-thread-menu
Depends on D6863
Test Plan:
Confirmed that the menu appears and pushes the modal on screen
Reviewers: atul, ginsu, tomek, ashoat
Reviewed By: ashoat
Subscribers: ashoat
Differential Revision: https://phab.comm.dev/D6864