GitLab is used only for code review, issue tracking and project management. Canonical locations for source code are still https://gitweb.torproject.org/ https://git.torproject.org/ and git-rw.torproject.org.
many modules are very old and should be modernized and refactured
this is a bigger task ticket is for planning the first steps.
depends on #19730 (moved)
see also #20049 (moved)