POC =act Make use of externalSubmit to yield.

[He-Pin]

refs: #661

Some previous work done by @jrudolph

The Current VirtualThrad in JDK 21 making use of the externalSubmit

if (s == YIELDING) {   // Thread.yield
            setState(RUNNABLE);

            // notify JVMTI that unmount has completed, thread is runnable
            notifyJvmtiUnmount(/*hide*/false);

            // external submit if there are no tasks in the local task queue
            if (currentThread() instanceof CarrierThread ct && ct.getQueuedTaskCount() == 0) {
                externalSubmitRunContinuation(ct.getPool());
            } else {
                submitRunContinuation();
            }
        }

I think this change will affect the performance.