GeezerVison

… async functions

…25862

…zy import inspect

ContextDecorator's generator wrapper now uses ``return (yield from gen)``
so a wrapped generator's StopIteration value is not lost.

Tests: drop the unused run_test() helper, normalize quote style, and add
exception-path and early-close coverage for the new generator and async
generator wrappers so closing()/aclosing() behavior is exercised.

Add versionchanged notes to ContextDecorator and AsyncContextDecorator
describing the new behavior when decorating generator, coroutine, and
async generator functions, and call out that asend()/athrow() are not
forwarded through the async generator wrapper.  Reword the
AsyncContextDecorator intro now that synchronous callables are accepted.

State the primary use (coroutine and async generator functions) up front
and move the synchronous-input behavior into a note that points users at
ContextDecorator when the calling convention change is not wanted.

The early-stop tests asserted ordering with comments that named closing()
and aclosing() as the reason; restate as the invariant being tested so
the comments stay correct if the implementation changes.

The sync generator wrapper uses ``yield from`` so .send() and .throw()
reach the wrapped generator; lock that in.  The async generator wrapper
re-yields with ``async for`` so asend()/athrow() do not reach the
wrapped generator; pin that documented behavior so a future change that
starts forwarding will fail and prompt a doc update.