Polygon 2D UV Editor: add button to clear all painted weights to skeleton bones

[hsandt]

In the same vein as godotengine/godot#24853, I've painted polygon 2D vertices with weights to bind them to Skeleton bones, but I'd like to clear them all to start from scratch now.

This is because I got multiple bugs, only the left side of the character has issues, so I suspect it is just a local misconfiguration. I don't want to recreate the Polygon2D from scratch, so being able to clear assigned Polygon metadata, and in particular painted weights which as not visible in Inspector unlike Points and UV, and therefore cannot be cleared by clicking the Revert button, would help a lot.

My first issue was that some polygon was shrinking in an odd way. I realized later that it was bound to the Hip (I didn't realize that selecting a different Bone in the Polygon 2D UV Editor > Bones > Sync Bones to Polygon > Bones radio list preserved painted weights on previously selected bones), and I had to clear Hip weights manually.

The second issue is that my polygon completely disappears at high rotation angles. I haven't solved this one yet so I don't even know what's causing it.

See left shoulder green polygon in the GIF below:

I'll submit a bug report, but it's likely I did some bad configuration on my side. If I could clear painted weights, and in fact all properties one by one from the Polygon 2D UV Editor, by checking when the issue is solved and then looking at git diff, I'd be able to understand where the issue came from on my own.

This is almost a feature proposal, but I'm new to the Polygon 2D UV Editor so I may missing something. So I open a discussion first.

[hsandt]

So for the specific issue shown in the GIF, I found it to have already been reported: godotengine/godot#74132
and I used the mentioned workaround (move root closer to polygon) to fix it.

My proposal is still worth to help working with weight painting though.