[Suggestion] Reproducing parts_visibility in Blockbench

[Cub0use]

The idea is to have a tab similar to "Variable Placeholders", named "Parts Visibility" or something, in reference to this property in Minecraft Bedrock's Render Controllers. In this tab, you could type in the names of bones and some molang (that can reference variable placeholders, or variables set in the timeline) to determine their visibility (same behavior as the RC).

For instance: head = 0 leftArm = !v.armcut leftArm_cut* = v.armcut

One of the main use cases of this would be for specific setups where you want some of the bones' position, rotation and scale to interpolate between two animations (by setting some blend_transition time in the Animation Controller State), but some other bones to disappear or appear instantly.

This would allow to preview in Blockbench the combined use of animations and Parts_visibility, and avoid having to use more molang in scale keyframes to hide or show some bones, or manually toggling the visibility of multiple bones to obtain the same result.