[mlir][CSE] Add ability to remove commutative operations

This patch takes advantage of the Commutative trait on operation
to remove identical commutative operations where the operands are swapped.

The second operation below can be removed since `arith.addi` is commutative.
```
%1 = arith.addi %a, %b : i32
%2 = arith.addi %b, %a : i32
```

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D123492