Summary:
Regularization added for caffe2 and dper.
This regularization is intended for `dense feature `only. Sparse feature would serve as individual optimizer, see ` D5618405 ` and `D5534579` for details.
The implementation of dense regularization is similar to the ones in optimizer. we now support `l1 norm` and ` l2 norm` in regularizer. In dper, we would call different regularization based on regularization type defined in model_definition.thrift.
Reviewed By: xianjiec
Differential Revision: D5724851
fbshipit-source-id: 0fbee698cfeff1ac477fc9d07785406069f8d9c8
