Multiplatform Matrix client

It uses a Rust library built on top of matrix-sdk for the core Matrix
functionality and a Compose Multiplatform UI for Android and desktop.

Current capabilities:
- room list with basic previews and unread counts
- room and thread timelines (text and media)
- end-to-end encryption (via matrix-sdk)
- spaces view
- basic presence and privacy settings

Do donate if you'd like to (not going to have it in app, wouldn't be here too but need a justification for me or my SOs)
