Add labs flag for Threads Activity Centre (#12137)

* Add `Thread Activity centre` labs flag

* Rename translation string

* Update supportedLevels

* Fix labs subsection test

* Update Threads Activity Centre label

* Make threads activity centre labs flag split out unread counts

Just shows notif & unread counts for main thread if the TAC is enabled.

* Fix tests

* Simpler fix

* Pass in & cache the status of the TAC labs flag

* Pass includeThreads as setting to doesRoomHaveUnreadMessages too

* Fix tests

---------

Co-authored-by: David Baker <dbkr@users.noreply.github.com>

src/settings/Settings.tsx

@@ -81,6 +81,7 @@ export enum LabGroup {
     Spaces,
     Widgets,
     Rooms,
+    Threads,
     VoiceAndVideo,
     Moderation,
     Analytics,
@@ -104,6 +105,7 @@ export const labGroupNames: Record<LabGroup, TranslationKey> = {
     [LabGroup.Spaces]: _td("labs|group_spaces"),
     [LabGroup.Widgets]: _td("labs|group_widgets"),
     [LabGroup.Rooms]: _td("labs|group_rooms"),
+    [LabGroup.Threads]: _td("labs|group_threads"),
     [LabGroup.VoiceAndVideo]: _td("labs|group_voip"),
     [LabGroup.Moderation]: _td("labs|group_moderation"),
     [LabGroup.Analytics]: _td("common|analytics"),
@@ -1113,6 +1115,14 @@ export const SETTINGS: { [setting: string]: ISetting } = {
         supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         default: [],
     },
+    "threadsActivityCentre": {
+        supportedLevels: LEVELS_ACCOUNT_SETTINGS,
+        labsGroup: LabGroup.Threads,
+        controller: new ReloadOnChangeController(),
+        displayName: _td("labs|threads_activity_centre"),
+        default: false,
+        isFeature: true,
+    },
     [UIFeature.RoomHistorySettings]: {
         supportedLevels: LEVELS_UI_FEATURE,
         default: true,