[mlir][openacc] Restore unit tests for device_type functions (#77122)

These tests were initially pushed together with
https://github.com/llvm/llvm-project/pull/75864 but they were triggering
some buildbot failure (sanitizers). They now make use of the
`OwningOpRef` so all the resources are correctly destroyed at the end of
each tests.
They will be extended to includes all the extra getter functions added
with device_type support.