[web] Handle clicking on notifications

Summary:
When user clicks a notification we want to:

• if a comm tab is already focused navigate to a correct thread
• if it's not focused we want to focus it
• if all tabs are closed we want to open a new tab

Test Plan: Check if tab navigates to a thread, focuses if needed. Check that a tab is created if needen.

Reviewers: tomek, kamil, inka

Reviewed By: inka

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D6835