Unify the way we decide whether a room is a DM or a group room (#3100)

* Add centralised 'room is DM' check

Also add extension functions for `MatrixRoom` and `MatrixRoomInfo`.

* Use the centralised method and extension functions through the app, including:

- Room list.
- Room details screen.
- Invites.
- Notifications.

Replace most `isDirect` usages with `isDm`.

* Update screenshots

---------

Co-authored-by: ElementBot <benoitm+elementbot@element.io>

features/leaveroom/impl/src/main/kotlin/io/element/android/features/leaveroom/impl/DefaultLeaveRoomPresenter.kt

@@ -34,6 +34,7 @@ import io.element.android.libraries.di.SessionScope
 import io.element.android.libraries.matrix.api.MatrixClient
 import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.room.RoomMembershipObserver
+import io.element.android.libraries.matrix.api.room.isDm
 import kotlinx.coroutines.launch
 import timber.log.Timber
 import javax.inject.Inject

features/leaveroom/impl/src/test/kotlin/io/element/android/features/leaveroom/impl/DefaultLeaveRoomPresenterTest.kt

@@ -119,7 +119,7 @@ class DefaultLeaveRoomPresenterTest {
             client = FakeMatrixClient().apply {
                 givenGetRoomResult(
                     roomId = A_ROOM_ID,
-                    result = FakeMatrixRoom(activeMemberCount = 2, isDirect = true, isOneToOne = true),
+                    result = FakeMatrixRoom(activeMemberCount = 2, isDirect = true),
                 )
             }
         )