Add the ability to freeze an axis for twist bone rotations

[dan9070]

I noticed that while importing a model, I had no way of freezing an axis for twist bones to work upon. They seemingly affect all three axis if I throw the bone into the twist bones slot in "Twist Bones" in the avatar script.

For PC, I'd just use the rotation constraint component instead of in the avatar script to be able to freeze an axis, but that can't be done on quest seemingly since the rotation constraint component doesn't seem to work at all on quest. If it's possible to add the ability to lock rotation constraints for the avatar script for twist bones that'd be amazing.

[Woogoo336]

Good to know about the rotation constraints. I'm getting reports of my avatar that depends on them not working correctly on quest. I guess that should be another bug report.