Add total unread notification count to home screen (#7891)

* Add total unread notification count to home screen

This will be calculated on each sync heartbeat (for now, using the state updates for the room list service).

* Simplify `counter` parameter logic

* Read the total unread count when the home screen is first displayed

---------

Co-authored-by: Benoit Marty <benoitm@element.io>

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/FakeMatrixClient.kt

@@ -102,6 +102,7 @@ class FakeMatrixClient(
     override val mediaPreviewService: MediaPreviewService = FakeMediaPreviewService(),
     override val roomMembershipObserver: RoomMembershipObserver = RoomMembershipObserver(),
     private val homeserverCapabilitiesProvider: FakeHomeserverCapabilitiesProvider = FakeHomeserverCapabilitiesProvider(),
+    private val totalUnreadCountResult: () -> Result<Long> = { Result.success(0L) },
     private val accountManagementUrlResult: (AccountManagementAction?) -> Result<String?> = { lambdaError() },
     private val resolveRoomAliasResult: suspend (RoomAlias) -> Result<Optional<ResolvedRoomAlias>> = {
         Result.success(
@@ -468,4 +469,8 @@ class FakeMatrixClient(
     override fun homeserverCapabilities(): HomeserverCapabilitiesProvider {
         return homeserverCapabilitiesProvider
     }
+
+    override fun totalUnreadCount(): Result<Long> {
+        return totalUnreadCountResult()
+    }
 }

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/sync/FakeSyncService.kt

@@ -11,6 +11,8 @@ package io.element.android.libraries.matrix.test.sync
 import io.element.android.libraries.core.coroutine.mapState
 import io.element.android.libraries.matrix.api.sync.SyncService
 import io.element.android.libraries.matrix.api.sync.SyncState
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 
@@ -33,6 +35,14 @@ class FakeSyncService(
 
     override val isOnline: StateFlow<Boolean> = syncState.mapState { it != SyncState.Offline }
 
+    private val heartBeatFlow = MutableSharedFlow<Unit>(extraBufferCapacity = 1)
+
+    override val heartBeat: Flow<Unit> = heartBeatFlow
+
+    suspend fun emitHeartBeat() {
+        heartBeatFlow.emit(Unit)
+    }
+
     suspend fun emitSyncState(syncState: SyncState) {
         syncStateFlow.emit(syncState)
     }