Summary:
Migrate experiments folder to fb/sparse folder. Keep FunHashOp and SparseFunHashOp because they are now assumed as a default Op in depr. What I did
# Migrate FunHashOp and SparseFunHashOp and their unitests to core-caffe2, make sure tests are passed.
# Migrate other Ops in experiment folder to fb/sparse folder. Write new TARGETS files for them. Make sure tests are passed.
# Make sure all related tests passed.
# Fix MKL definition btw. Make sure that FC_Sparse is not compiled when there is no MKL support
Reviewed By: salexspb
Differential Revision: D4952993
fbshipit-source-id: 86c03676ab4e47f04d2d0dd438a4a1c849bbbff0