Based on the design of #102585, This PR replaces the MOD_MASK icon with the CLIP_UVDEHLT icon to better communicate the intent of masking across many areas of Blender. It also changes the Grease Pencil `invert` icons to avoid conflicts with the CLIPUV_DEHLT & CLIPUV_HLT. Pull Request: https://projects.blender.org/blender/blender/pulls/117467