[MLIR][OpenMP] Update op verifiers dependent on omp.wsloop (2/5)

This patch updates verifiers for `omp.ordered.region`, `omp.cancel` and
`omp.cancellation_point`, which check for a parent `omp.wsloop`.

After transitioning to a loop wrapper-based approach, the expected direct
parent will become `omp.loop_nest` instead, so verifiers need to take this into
account.

This PR on its own will not pass premerge tests. All patches in the stack are
needed before it can be compiled and passes tests.