Support Matrix URI scheme

[ShadowJonathan]

Google allows apps to specify a custom URI handler, with the merge of the Matrix URI proposal, this means that the URI can be referenced from links, redirects, and other formats.

[hex-m]

The URI handler is one missing part, but the more basic one would be support for interpreting Matrix URIs in the client itself. Currently if you e.g. write matrix:r/weruletheworld:example.org in a chat it is not recognized as a link.

[Mikaela]

Apparently when you currently open a Matrix URI scheme link opens FluffyChat iif installed and we just had a very good laugh offline for trying to open one 😂