Fix region_filter_clip_enabled to avoid sprite bleeding for interpolated sprite sheets

[patowen]

Fixes #87847

This PR modifies the fix done in #12828 to reintroduce the half_texpixel offset but fix the bug in the original implementation that led to #11417.

My understanding is that the intent of this code was originally to clamp the UV-coordinates to the centers of the outermost texels, which achieves the desired effect of avoiding any sprite bleeding caused by linear interpolation. I believe this was conceptually correct, but a math error resulted in #11417.

[patowen]

I marked this PR as a draft because I think it might be worthwhile to update the description of region_filter_clip_enabled in the same PR, since "the outermost pixels get blurred out" don't seem to accurately describe this attribute, but I haven't decided on the right wording for it yet (and am open to suggestions).

EDIT: I found existing documentation in AtlasTexture.xml for the same feature, so I updated the documentation in Sprite2D.xml to match.

[clayjohn]

Looks great! Thanks for updating the documentation as well.

I tested on the MRPs from #87847 and #11417 and confirm that this fixes the former without re-introducing the issue from the latter.

[clayjohn]

The final step before merging is to squash all the commits together so that the whole PR only contains 1 big commit with all your changes. We like to merge one commit at a time to keep the git history clean and navigable.

If you don't know how to do that, we have a helpful tutorial in the official documentation https://docs.godotengine.org/en/latest/community/contributing/pr_workflow.html#the-interactive-rebase

[patowen]

Makes sense to me, thanks! I went ahead and squashed the commits.

[patowen]

Based on the latest build error, I believe the "Android / Template arm32" check needs to be rerun, as the failure seems intermittent and unrelated to my changes. I don't believe I have permission to do this myself.

EDIT: Thanks for rerunning the checks!

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[MeanRaccoon]

Cool, it's nice to see people working on the bugs we find eventually. Keep up!