Ensure roomId are not rendered in the UI.

Add preview to see the effect.
Use RoomAvatar data fallback everywhere, to not use roomId (`!` char) for the avatar initial, but rather `#`.

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/RoomSummaryDetailsProvider.kt

@@ -29,12 +29,13 @@ open class RoomSummaryDetailsProvider : PreviewParameterProvider<RoomSummaryDeta
     override val values: Sequence<RoomSummaryDetails>
         get() = sequenceOf(
             aRoomSummaryDetails(),
+            aRoomSummaryDetails(name = null),
         )
 }
 
 fun aRoomSummaryDetails(
     roomId: RoomId = RoomId("!room:domain"),
-    name: String = "roomName",
+    name: String? = "roomName",
     canonicalAlias: RoomAlias? = null,
     isDirect: Boolean = true,
     avatarUrl: String? = null,

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/SelectedRoom.kt

@@ -62,7 +62,8 @@ fun SelectedRoom(
         ) {
             Avatar(AvatarData(roomSummary.roomId.value, roomSummary.name, roomSummary.avatarUrl, AvatarSize.SelectedRoom))
             Text(
-                text = roomSummary.name,
+                // If name is null, we do not have space to render "No room name", so just use `#` here.
+                text = roomSummary.name ?: "#",
                 overflow = TextOverflow.Ellipsis,
                 maxLines = 1,
                 style = MaterialTheme.typography.bodyLarge,