[mlir][tosa] Moves constant folding operations out of the Canonicalizer

Transpose operations on constant data were getting folded during the
canonicalization process. This has compile time cost proportional to
the constant size. Moving this to a separate pass to enable optionality
and flexibility of how such scenarios can be handled.

Reviewed By: rsuderman, jpienaar, stellaraccident

Differential Revision: https://reviews.llvm.org/D124685