[mlir] Support full commutative operation equality (#192652)

Previous, commutative equality only works if the operand lists are
exact permutations of one another.
By treating the `equivalentValues` map as a map onto a common set of
values, we can achieve full commutative equality.

GitOrigin-RevId: bd5b29314660232e74a43b684cbecf6f0c1e3983