[OpenMP] Move synchronization into `__tgt_async_info`

The AsyncInfo should be passed everywhere and it should offer a way to
ensure synchronization, given a libomptarget Device.

This replaces D96431.

Reviewed By: tianshilei1992

Differential Revision: https://reviews.llvm.org/D96438

GitOrigin-RevId: a2fc0d34db72315f05b96681013e1e16d4df41c7
3 files changed