[Feature] skeleton/pose annotation

[clover978]

Is your feature request related to a problem? Please describe.
I have invastaged a mount of open-source annotation tools, and I found all-most all of them do not support skeleton annotation. To my understanding, skeleton annotation can be formulated by a set of points connected by a specific manner, which is mostly like a combination of createPoint and createLineStrip.
Is there any out-of-scope technique obstacles to develop such feature ?

Describe the solution you'd like
Pre-define a skeleton template by providing a config file or by setting attirbutes to skeleton shape in GUI. Then create/edit a set of points which are connected by a specific manner.

Describe alternatives you've considered
None

Additional context
None