Utility: Create Virtual Hand

[jsprenger2]

Create a helper function to spawn Hands for reach and grasp points with the respective scripts for extracting constraints.

[jsprenger2]

Ideally we should have the option to generate grasp points for specific target avatars, hence scaling the hand w.r.t. the intended avatar. If no avatar is provided, we just take a default scale.

[jsprenger2]

In addition, the hand should be adjusted w.r.t. two aspects:

(1) the visualization should be a proper meshed hand. Maybe as well the copy of the hand of the target avatar (if possible?) or just a deformable model. this would help with getting the distances to the object right and reduce mesh collisions.

(2) using single-chain IK on each finger would allow for adjusting the position of the finger tips only, with the rest of the hand following.