Fix up pointer constraint interaction with tablet input

[Xyene]

Fixes #5268.

The less-obvious part of this change is in the second commit, with the (unexpected) problem described in its message. By my understanding of the pointer constraint spec this should be correct, but I wouldn't bet on my understanding :)

[emersion]

This commit addresses this behavior by only warping on the first surface commit since the pointer constraint was added.

Hmm, I don't think this is correct. If the pointer is confined and the surface changes the confine region, we should probably wrap.

[Xyene]

I think you're right, I missed that there's a set_region request and assumed a new region would create a new confine, but that's not the case.

Part of the issue here is that wlroots handles confine regions transparently, and doesn't explicitly notify sway when they change. Instead, since it has no information to the contrary, sway performs warping logic on every surface commit regardless of if the region has changed.

I think a solution here would be to make wlroots signal sway when the region changes, so sway doesn't have to warp every commit. I'll take a look at doing that in a separate patch, and base this one off that if it ends up working.

[Xyene]

Alright, I've split off the pointer region warping into swaywm/wlroots#2191 and #5334; this PR contains just the remaining logic to allow tablet input to leave the confine. With the other two commits applied, the issue remains resolved.

[emersion]

This approach looks good. Thanks!