Subject: Support usertags

From: Arun Isaac <[email-masked]>
Date: Sun, 23 Feb 2025 22:04:17 +0000

`mumi command' only supports the list of standard tags defined at
https://debbugs.gnu.org/Developer.html#tags It should also support other
Debbugs' usertags using the same unified interface. See
https://guix.gnu.org/manual/en/html_node/Debbugs-Usertags.html See
https://libreplanet.org/wiki/Group:Guix/PatchReviewSessions2024 for how
we user usertags at Guix.