[mlir][arith] Add initial files for (runtime) integration tests

The goal is to have a set of runtime tests for further extercise the
wide integer emulation pass and its conversion patterns. This was
suggested by @Mogball in D133629.

Add a minimal runtime test to demonstrate that printing and pass
pipeline works as expected.

Reviewed By: Mogball

Differential Revision: https://reviews.llvm.org/D134004