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
* fix: menu item with float value incorrectly generates bool parameter
* fix: reactive components generate transitions with overlapping condition ranges
* chore: add tests for menu item parameter type
* fix: incorrect parameter type detemination for float values
* chore: add more tests for menu item parameter type
* refactor: unify logic to determine parameter type and rename confusing variable
