Improve resiliance of SDK clients against server errors when searching a chat stored in the RAM:

Ensure that linphone_core_search_chat_room_2 doesn't do a SIP address comparison as stated in the RFC. In fact, doing that leads to being too exposed to server instabilities. For example, if a server for whatever reason removes the conf-id parameter from the chatroom peer address, it will prevent to client to join any new chatroom as all will match the corrupted chat