Refactor the JoinRoom screen to take advantage of newer APIs and support more joinRule/membership combinations (i.e. invite required, restricted, banned) (#3685)

- expose the full RoomPreview and RoomMembershipDetails through their own proxies
- implement standard mocks for all the different combinations
- converge on a single room info provider
- rebuild all the previews
- prioritise the preview data over the room one.

ElementX/Sources/Services/Room/RoomInfoProxy.swift

@@ -113,6 +113,9 @@ struct RoomPreviewInfoProxy: BaseRoomInfoProxyProtocol {
     var isSpace: Bool { roomPreviewInfo.roomType == .space }
     var activeMembersCount: Int { Int(roomPreviewInfo.numActiveMembers ?? roomPreviewInfo.numJoinedMembers) }
     
+    var joinRule: JoinRule { roomPreviewInfo.joinRule }
+    var membership: Membership? { roomPreviewInfo.membership }
+    
     /// The room's avatar info for use in a ``RoomAvatarImage``.
     var avatar: RoomAvatar {
         if isDirect, avatarURL == nil {