feature(room preview): Add option to forget room, improve the room preview screen for banned rooms.

Some internal refactoring was done too:
- Remove RoomInfo.isPublic to only use JoinRule.
- Also take into account restricted access rooms for previews.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/messagecomposer/suggestions/SuggestionsPickerView.kt

@@ -149,6 +149,7 @@ internal fun SuggestionsPickerViewPreview() {
             normalizedPowerLevel = 0L,
             isIgnored = false,
             role = RoomMember.Role.USER,
+            membershipChangeReason = null,
         )
         val anAlias = remember { RoomAlias("#room:domain.org") }
         SuggestionsPickerView(