Matrix Gateway: transform Matrix IDs into XMPP IDs that can just be clicked to join

[erebion]

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Is your feature request related to a problem? Please describe.

noope

Describe the solution you'd like

The Matrix Gateway could take Matrix IDs and convert them to XMPP IDs, so that those can simply be clicked to join another chat.

Currently, if anyone posts something like this:

#room:example.org

I have to transform it manually like this:

#room%example.org@matrix.example.net (or similar)

Instead of memorising the syntax, it'd be much easier to have that converted automatically, using the XMPP URI Scheme.

Describe alternatives you've considered

Additional context