[StableHLO] Port missing pointwise op tests (#13052)

I went over the list of all pointwise ops that we currently handle.
These fell through the cracks during the initial import (#12957).

Two ops are not tested: `ComplexOp` and `NotOp`, but these do not have
any tests in mlir-hlo either.

Next, I plan to split the linalg lowering tests into a few smaller test
files.

Issue: #12678