This change reworks delete handling to be more consistent with other properties,
by treating it as a virtual property (`deletedShape.{blendshapeName}`) instead of
a weird additional field of blendshape keys. This then fixes a number of issues
(e.g. broken preview for delete keys).
Fixes: #1253
* feat: add material switcher
Also refactor everything...
* refactor: simplify object curve handling
* refactor: additional refactoring and bugfixes
* feat: inverse mode
* feat: add material setter inspector UI
* chore: set material setter icon
* chore: fix error on build
* chore: adjust order of inverted element