Track explicit sync progress

[TLATER]

Very close now, looks like ~these PRs are left before it works on sway:

• https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4715
• Add support for linux-drm-syncobj-v1 swaywm/sway#8156

[fpletz]

Both have been merged. 🍻

[GrabbenD]

Some part of the pipline like the cursor pane aren't using Explicit Sync yet

Check Follow-up work section here https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4715

[TLATER]

:) Yeah, does seem to be sufficient to solve most flickering issues though from what I've heard.

Since this is for my dotfiles, I'll keep this open until it's working on my end, and I'll at least wait for the relevant sway/wlroots releases rather than using stuff straight from master.