GROMACS

The StatePropagatorDataGpu currently is one way or another responsible for:
1. Low-level data management.
2. Stream/context management.
3. Locality management.
4. Managing the copy events.

Proposed development is to introduce the "ManagedDeviceBuffer" object that will take these responsibilities away from the StatePropagatorDataGpu, making it into a collection of the respective buffers. The "ManagedDeviceBuffer" can also replace the StatePropagatorDataGpu in places, where only one buffer is needed, e.g. in PME-only ranks and tests.

1. https://gerrit.gromacs.org/#/c/gromacs/+/14599/ - Introduce a managed GPU buffer.
2. https://gerrit.gromacs.org/#/c/gromacs/+/14600/ - Make use of ManagedDeviceBuffer in StatePropagatorDataGpu.
3. https://gerrit.gromacs.org/#/c/gromacs/+/15417/ - Move wcycle management from state propagator data to managed device buffer.
4. https://gerrit.gromacs.org/#/c/gromacs/+/14637/ - Use the methods of ManagedDeviceBuffer directly.
5. https://gerrit.gromacs.org/#/c/gromacs/+/14646/ - Create a constructor for the ManagedDeviceBuffer that takes only one stream.
6. https://gerrit.gromacs.org/#/c/gromacs/+/14644/ - Use ManagedDeviceBuffer instead of StatePropagatorDataGpu in PME-only ranks and tests.