various not push related notification improvements (#4929)

- support new notification type `severed_relationships`, closes
https://github.com/tuskyapp/Tusky/issues/4835, closes
https://github.com/tuskyapp/Tusky/issues/4334
- support new notification type `moderation_warning`
- the account note is now shown again for follow request and follow
notifcations (was broken since
https://github.com/tuskyapp/Tusky/pull/4026)
- closes https://github.com/tuskyapp/Tusky/issues/4571
- The "unknown notification type" notification now shows the unknown
type and a info dialog when you click it
https://chaos.social/@ConnyDuck/113601791254050485
- The notification policy banner in the notification tab is now cached
for better offline behavior (and less jumping of the list on every load)
and updates when interacting with the requests
- Fixes a bug where some notifications wouldn't be filtered correctly.
Behavior should now match Mastodon.
https://mastodon.social/@alm10965/113639206858728177
- Fixes a bug where some system notifications wouldn't have a body
- For filters and channels, report and signup notifications are now
grouped as "Admin", severed relationship events and moderation warnings
as "other". These lists are super long already.
- The icon for the "`<user>` just posted" notification is now a bell
instead of a home
- Follow requests won't be filtered by default in the notification tab.
No idea why this one got special treatment. This change will only affect
new logins and not existing ones.
- closes #4440 
- Adds info about attached media or poll to
StatusNotificationViewHolder. This is important context that has been
missing before.
- Adds (private) reply/(private) mention text above mention
notification. (Partially?) closes
https://github.com/tuskyapp/Tusky/issues/3883

Some screenshots:

![follow](https://github.com/user-attachments/assets/5f962116-c16f-4574-aae1-b1f931ce1508)

![moderation_warning](https://github.com/user-attachments/assets/55a2ee7e-ebcd-4ae8-9170-f07f9f5df5d2)

![severed_relationship](https://github.com/user-attachments/assets/a8d6b898-eb44-43b4-9b6d-3fb5f7aeb852)

![unknown](https://github.com/user-attachments/assets/c74ee33e-6926-42b1-b952-dc888b72fd27)

![unknown_info](https://github.com/user-attachments/assets/19ff11bf-aaff-4219-87e2-ea980ebbd118)

![notifications](https://github.com/user-attachments/assets/b5021cbb-f6c0-4a17-9e15-73e669504647)

app/src/main/java/com/keylesspalace/tusky/MainViewModel.kt

@@ -132,7 +132,7 @@ class MainViewModel @Inject constructor(
                         if (event.accountId == activeAccount.accountId) {
                             val hasDirectMessageNotification =
                                 event.notifications.any {
-                                    it.type == Notification.Type.MENTION && it.status?.visibility == Status.Visibility.DIRECT
+                                    it.type == Notification.Type.Mention && it.status?.visibility == Status.Visibility.DIRECT
                                 }
 
                             if (hasDirectMessageNotification) {