Prepare mutter 44~rc

Here's the start of packaging 44~rc. I am not pushing directly to debian/master (which has 44~beta) because we need to update some patches first and that leaves debian/master open in case we want to do any urgent fixes first.

TODO

• @3v1n0-guest Please check if we still need debian/backends-native-kms-crtc-Don-t-compare-gamma-values-on-un.patch and update it if we do. It's a small patch at least!
• @vanvugt-guest How do you want to handle the triple buffering patch? Updating Lunar to 44~rc isn't urgent as long as 44~beta is stuck in lunar-proposed behind glib
• @3v1n0-guest Although it's not in this branch, I expect Ubuntu's x11-Add-support-for-fractional-scaling-using-Randr.patch will need to be updated for the new fractional scaling protocol implementation.
• We probably still have autopkgtest failures to figure out