kernel: workq: Add internal function z_work_submit_to_queue()

This adds the internal function z_work_submit_to_queue(), which
submits the work item to the queue but doesn't force the thread to yield,
compared to the public function k_work_submit_to_queue().

When called from poll.c in the context of k_work_poll events, it ensures
that the thread does not yield in the context of the spinlock of object
that became available.

Fixes #45267

Signed-off-by: Lucas Dietrich <ld.adecy@gmail.com>