Add irc:// URL support to profile metadata

[emersion]

Pitch

Allow adding irc:// and ircs:// URLs to profile metadata and make them clickable.

At the moment, they render as plain text.

Motivation

I'd like to add an ircs://irc.libera.chat/emersion link to my Mastodon account, so that people can just click it to chat with me.

Project accounts might want to link to their IRC channel.

[duxsco]

Keyoxide handles IRC the following way:
https://docs.keyoxide.org/service-providers/irc/