[web] Filter available chats based on the picked community

Summary:
issue: https://linear.app/comm/issue/ENG-3176/make-pressing-a-drawer-item-in-chat-tab-filter-available-chats
We want the list of chats in ChatThreadList to be filtered based on the currently selected community in the Chat tab

Test Plan:
Checked that if a community is set in state.pickedCommunityIDs.chat, then ChatThreadList displays only chats from that community
Checked that the Background tab also works

Reviewers: kamil, tomek, michal

Reviewed By: kamil

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D6971