TPA-RFC-22: rename IRC channel

https://gitlab.torproject.org/tpo/tpa/team/-/wikis/policy/tpa-rfc-22-rename-irc

this was originally just done as an email to the list, but it is more involved that i thought, because bots.

so, checklist:

• create new registered IRC channel
• change topic on old IRC channel, add ENTRYMSG
• warn people about the change again
• change KGB-TPA to point to new channel
• change tor bot to new channel (@ahf)
• change zwiebelbot to new channel (@weasel)
• change nsa bot to new channel (@weasel - this also involved changing the target in gitolite and /srv/puppet.torproject.org/git/hooks/nsa-bot on pauli)
• bridge with matrix (@ahf)
• wait for people to leave
• make the old channel +m or +i