Add TRMF

[WenjieDu]

1. Model description

Add TRMF Temporal regularized matrix factorization for high-dimensional time series prediction as an imputation method.

@article{yu2016temporal,
  title={Temporal regularized matrix factorization for high-dimensional time series prediction},
  author={Yu, Hsiang-Fu and Rao, Nikhil and Dhillon, Inderjit S},
  journal={Advances in neural information processing systems},
  volume={29},
  year={2016}
}

2. Check open-source status

• The model implementation is publicly available

3. Provide useful information for the implementation

https://github.com/SemenovAlex/trmf not official code

[WenjieDu]

There're still some issues in the current implementation #556 :

1. TRMF implementation hasn't been integrated into PyPOTS framework yet;
2. no testing cases for TRMF imputation method;

I'm working on this and will make a PR to fix these.