Feature: legs and hips tracking

[FarzanAlipour]

Hey,
I checked the repo and it is super nice!
I wanted to know if you have any plans to track legs and hips in this package
P.N : I have used the same logic for legs and hips but it is not as good as arms.

[Neleac]

I also tried using the same logic and the results are not great, see fullbody branch. I suspect the problem is the initial landmark-avatar alignment. I simply rotate the landmarks to match the hips by comparing 2 vectors, but this should actually be a 3D coordinate alignment calculation.

[FarzanAlipour]

sorry for the delay.
I have checked the fullbody branch, and yes the results are not good.
I achieved a better result with caching the spine and hip upward direction in the Start and then calculate the FromToRotation for the cached vector and mediapipe* upward for hips and spine ( *which are calculated in a separate method)