For now everything should look identical. However this moves to using a model for the content of the message and is intended to lay the foundation for improved message content representation, e.g. splitting up a text message in multiple sections and using different delegates for things like code and quotes.
Pull the generic aspects from Room search and join room pages into it's own component. This is done in anticipation of using the new generic search page for a user search functionality.
- `SearchPage` is now used for the generic version with the old one being renamed `RoomSearchPage`
- `JoinRoomPage` is renamed to `ExploreRoomsPage` inline with everywhere else in NeoChat
There is also some cleanup of the code for both search pages in here.
Similar to text handler, pull out the disparate array of functions which format information from an event ready for display in the UI and put in a handler class with a test suite.
requires https://github.com/quotient-im/libQuotient/pull/686
