On some projects, the sprite image changes frequently, which can cause global layouts and paints if we arent careful. Use the same absolute positioning strategy from the sprite library animations to contain layouts to the sprite image itself

Fixes useability issue where the drop area was too small, and you couldn't see it.

The blend-mode property was being set on the whole thing, rather than the image only

* Fix all the little RTL layout bugs

- [ ] borders on toolbox and workspace mirror correctly
- [ ] spacing on stage selector is correct
- [ ] stage size icons are mirrored
- [ ] extension library coming soon text is positioned correctly
- [ ] only mirror blocks icon on the tab (others stay right-handed)
- [ ] drop down icon in create variable modal has correct spacing

* FIx RTL backpack header border-radius

* round the bottom corner of paint/sound editors

This makes the editor’s asset panels match the blocks.