[web] Add calendar filter type for displaying only one community
We want to be able to press some button, and see only chats from a given community to be visible in the calendar filters. We want this information to persist when switching between tabs. So we will keep
this as a calendar filter in redux.
This diff introduces the architectural changes required for this - adding and changing types according to what will be needed.
Test Plan: Run web app, check that calendar filters work like they used to.
Reviewers: kamil, tomek, ashoat
Reviewed By: tomek
Subscribers: ashoat, atul
Differential Revision: https://phab.comm.dev/D6457