Port in `lgssm_posterior_sample` function

[ezhang94]

Closes #4

Scales for masked dynamics noise and masked observation noise are currently hardcoded in, i.e. in

• jax_moseq/models/keypoint_slds/gibbs.py :: resample_locations, and
• jax_moseq/models/keypoint_slds/gibbs.py :: resample_continuous_stateseqs

I would suggest setting these as parameters that can be passed in, so that they can be appropriately set, relative to the data noise, but I think they should do for now.

Results from demo notebook, using example data

Fitted AR-HMM

Fitted keypoint-SLDS

[calebweinreb]

How did you choose 10 for the masked noise/dynamics? Why not something bigger like 1e6?