Unify sync tests #1763

Is your feature request related to a problem? Please describe.

Currently, we have synchronization tests for CUDA and OpenMP in the "old-tests" directory, HIP synchronization test in the test/unit/hip directory, and no synchronization tests for SYCL.

Describe the solution you'd like

Rework the existing sync tests, and add missing tests, so that they live in one place and are parametrized similar to other tests so that there is one implementation that tests each back-end.