This PR moves back the wireframe slider option back to the
bones overlay popover. It is only showed in paint weight mode
and only active if in wireframe mode.
It was concluded that this feature should be revisited to maybe
cover all shading modes in the future. But for now it is safer
for 4.5 to limit it to the weightpaint mode.
Pull Request: https://projects.blender.org/blender/blender/pulls/140276
b1f222648d