Only fetch and display a given notification once (#3626)

When fetching:

- Maintain a marker with the position of the newest fetched notification
- Use the marker to determine which notifications to fetch
- Fetch notifications with min_id to ensure that none are lost
- Update the marker as necessary
- Perform a one-time immediate fetch of notifications on startup

When creating notifications:

- Identify each notification with tag=${MastodonNotificationId}, id=${account.id}
- Remove activeNotifications field, it's no longer necessary
- Use the tag/id tuple to reliably identify existing notifications and avoid creating duplicates
- Cancelling notifications for an account must iterate over all the notifications, and individually remove the notifications that exist for that account.
- Limit notifications to a maximum of 40 (excluding summary notifications)
- Remove notifications (oldest first) to get under this limit
- Rate limit notification creation to 1 per second, so the OS won't drop them

Adjust the summary notification:

- Ensure the summary notification and the child notifications have the same group key
- Dismiss the summary notification if there is only one child notification

NotificationClearBroadcastReceiver is no longer needed, so remove it, and the need for deletePendingIntent.

Fixes #3625, #3539

app/src/main/java/com/keylesspalace/tusky/network/MastodonApi.kt

@@ -152,11 +152,19 @@ interface MastodonApi {
         @Query("timeline[]") timelines: List<String>
     ): Single<Map<String, Marker>>
 
+    @FormUrlEncoded
+    @POST("api/v1/markers")
+    fun updateMarkersWithAuth(
+        @Header("Authorization") auth: String,
+        @Field("home[last_read_id]") homeLastReadId: String? = null,
+        @Field("notifications[last_read_id]") notificationsLastReadId: String? = null
+    ): NetworkResult<Unit>
+
     @GET("api/v1/notifications")
     fun notificationsWithAuth(
         @Header("Authorization") auth: String,
         @Header(DOMAIN_HEADER) domain: String,
-        @Query("since_id") sinceId: String?
+        @Query("min_id") minId: String?
     ): Single<List<Notification>>
 
     @POST("api/v1/notifications/clear")