linux-dmabuf-v1: add helpers to generate tranches
Compositors can now set custom per-surface tranches, but it's a bit tedious: https://github.com/swaywm/sway/pull/6313
It would be nice to add helper functions to generate common tranches, e.g. the renderer tranche and the scanout tranche.
Need to think about memory management: the format set for each tranche needs to be free'd at some point. struct wlr_linux_dmabuf_feedback_v1_tranche
has it const
.