Initial support for DRM async page flip v2

[cmeissl]

Description

This is based on #1335, but takes a slightly different route.
Instead of calculating the PresentationMode inside DrmCompositor::render_frame it expects to receive
the desired mode.

This should allow the following things:

• more stable async page flip handling
  the implicit handling might not have enough information about user-preference and calculating it
  per frame could result in flip-flip between sync and async page flip which should be avoided imo
• implicit disable overlay planes (potentially allowing them in a future PR)
  this should increase the chance that we can fulfill the async request
• keep the decision a compositor policy

Note: This won't work as is on some intel hardware, because not all formats support async page flips.
I will try to come up with a solution, but that can wait for another day.

There is also a new environment variable in anvil to test this, running with ANVIL_FORCE_TEARING=1 should
enable it.

@PolyMeilex I opened a separate PR because I did not like to overwrite your wonderful work, but I kept you
as the main author. I hope you don't mind.

Checklist

• I agree to smithay's Developer Certificate of Origin.

[PolyMeilex]

Works as expected on my integrated AMD Radeon cards 👌

[EmanuelKroell]

Works as expected in Niri with very minor changes to it on AMD :) Thank you for the good work

[urayde]

Using #1946 + #1949 on NVIDIA Turing (with the nvidia-open proprietary driver) works fine, both on niri and anvil.

Worth noting that DRM debugger reports the following message:
[drm:drm_atomic_check_prop_changes] [PROP:18:IN_FENCE_FD] No prop can be changed during async flip
Couldn't reproduce it on other compositors such as Sway or Hyprland.

[shibahaczix]

I've been waiting for this for so long... 🥹

[cmeissl]

IN_FENCE_FD

Hm, IN_FENCE_FD was excluded from the things that are allowed to change, yeah. But as far as I know this limitation has been removed.