Notification policy (#4768)

This was so much work wow. I think it works pretty well and is the best
compromise between all the alternative we considered. Yes the
pull-to-refreh on the notifications works slightly different now when
the new bar is visible, but I don't think there is a way around that.

Things I plan to do later, i.e. not as part of this PR or release:
- Cache the notification policy summary for better offline behavior and
less view shifting when it loads
- try to reduce some of the code duplications that are now in there
- if there is user demand, add a "legacy mode" setting where this
feature is disabled even if the server would support it

closes #4331
closes #4550 as won't do
closes #4712 as won't do

<img
src="https://github.com/user-attachments/assets/de322d3c-3775-41e7-be57-28ab7fbaecdf"
width="240"/> <img
src="https://github.com/user-attachments/assets/1ce958a4-4f15-484c-a337-5ad93f36046c"
width="240"/> <img
src="https://github.com/user-attachments/assets/98b0482b-1c05-4c99-a371-f7f4d8a69abd"
width="240"/>

app/src/test/java/com/keylesspalace/tusky/components/notifications/NotificationsRemoteMediatorTest.kt

@@ -80,7 +80,7 @@ class NotificationsRemoteMediatorTest {
         val remoteMediator = NotificationsRemoteMediator(
             accountManager = accountManager,
             api = mock {
-                onBlocking { notifications(anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull()) } doReturn Response.error(500, "".toResponseBody())
+                onBlocking { notifications(anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull()) } doReturn Response.error(500, "".toResponseBody())
             },
             db = db,
             excludes = emptySet()
@@ -99,7 +99,7 @@ class NotificationsRemoteMediatorTest {
         val remoteMediator = NotificationsRemoteMediator(
             accountManager = accountManager,
             api = mock {
-                onBlocking { notifications(anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull()) } doThrow IOException()
+                onBlocking { notifications(anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull(), anyOrNull()) } doThrow IOException()
             },
             db = db,
             excludes = emptySet()