DPC++ daily 2022-09-01

[SYCL] Fix depends_on handling with pi commands (#5901)

Fixes two related issues:
1) if pi task is blocked by host task or host accessor it can not be enqueued and piEvent is not present in its event_impl. When we schedule new pi task with explicit (depends_on) dependency on the first one - its is absent in MDeps since we have no usual memory dependencies and present in MPreparedDepsEvents. MPreparedDepsEvents is used in enqueueImp for obtaining piEvents. Any events from MPreparedDepsEvents w/o pi events will be just skipped.
AddDep always call processDepEvent which distributes events to MPreparedDepsEvents (pi event expected) and MPreparedHostDepsEvents (no pi event) so replacement of MDeps in enqueueCommand should be valid.
2) if we have kernel w/o usual memory dependencies (MDeps & MUsers are empty) blocked kernel will be just "cleanup" and its execution will be skipped.

Signed-off-by: Tikhomirova, Kseniya <kseniya.tikhomirova@intel.com>