Properly summarize all notifications (#4848)

Do summary notifications like the Api defines it:
* Schedule and summarize without delay (in order for summerization to
work)
* Always have a summary notification: simplify code with this and make
more reliable
* Do not care about single notification count (the system already does
that as well)
* **Bugfix: Schedule summary first: This avoids a rate limit problem
that (then) not groups at all**

Testing this is probably the most difficult part.
For example I couldn't get any notification to ring with older Api
versions in the debugger. (Same as for current develop)
However one hack to always get notifications: Fix "minId" in
"fetchNewNotifications()" to a somewhat older value.


Next possible step: Have only one summary notification at all (for all
channels/notification types). You can still configure single channels
differently.
Or: For very many notifications: Only use a true summary one (something
like "you have 28 favorites and 7 boosts").

Generally: The notification timeline must be improved now. Because that
must be the go-to solution for any large number of notifications. It
must be easy to read. E. g. with grouping per post.

app/src/test/java/com/keylesspalace/tusky/MainActivityTest.kt

@@ -98,7 +98,7 @@ class MainActivityTest {
         NotificationHelper.createNotificationChannelsForAccount(accountEntity, context)
 
         runInBackground {
-            val notification = NotificationHelper.make(
+            val notification = NotificationHelper.makeBaseNotification(
                 context,
                 notificationManager,
                 Notification(
@@ -116,8 +116,7 @@ class MainActivityTest {
                     status = null,
                     report = null
                 ),
-                accountEntity,
-                true
+                accountEntity
             )
             notificationManager.notify("id", 1, notification)
         }