Transition to gitlab

Meta-bug for tracking remaining gitlab migration issues for Xorg projects.

• gitlab hosting migration
• Initial bugzilla migration (see freedesktop/freedesktop#40 (closed))
• BZ cleanup for xserver and major drivers
• BZ migration for xserver
• BZ migration for major drivers
• XCB BZ cleanup
• XCB repo migration
• XCB BZ migration
• Migrate bz's XStandards bugs
• Migrate bz's Xtests bugs to xorg/test/xts (also on freedesktop/freedesktop#40 (closed))
• Create archive map
• Archive old junk (in progress)