issue: https://linear.app/comm/issue/ENG-3179/make-the-badge-on-the-chat-tab-responsive-to-drawer-selection
We want the badge on the chat tab to display the number of unreads for the selected community.
This selector is almost identical to `unreadCount` selector that was used here before, for getting the number of all unreads, it only adds the `(!communityID || communityID ===
threadInfo.community)` condition