Tearing flip support

[YaLTeR]

Useful for games and stuff to get the lowest input latency.

We're mainly waiting for Smithay/smithay#1335 which is waiting for some driver stuff (?). Then on the niri side we can make tearing a window rule just like on-demand VRR.

There's also Smithay/smithay#1325 for the Wayland protocol, which is needed so windows can automatically request tearing without a manual window rule.