It introduces a pattern that swaps `linalg.generic + tensor.pack` to
`tensor.pack + linalg.generic`. It requires all the iteration types
being parallel; the indexing map of output operand is identiy. They can
all be relaxed in the future.
The user can decide whether the propagation should be applied or not by
passing a control function.
Reviewed By: mravishankar
Differential Revision: https://reviews.llvm.org/D138882
