Add support for ``trio >= 0.22`` and support for the new Python 3.11
``[Base]ExceptionGroup`` from `pep 654`_ via the backported
`exceptiongroup`_ package and some final fixes to the debug mode
subsystem.

This port ended up driving some (hopefully) final fixes to our debugger
subsystem including the solution to all lingering stdstreams locking
race-conditions and deadlock scenarios. This includes extending the
debugger tests suite as well as cancellation and ``asyncio`` mode cases.
Some of the notable details:

- always reverting to the ``trio`` SIGINT handler when leaving debug
  mode.
- bypassing child attempts to acquire the debug lock when detected
  to be amdist actor-runtime-cancellation.
- allowing the root actor to cancel local but IPC-stale subactor
  requests-tasks for the debug lock when in a "no IPC peers" state.

Further we refined our ``ActorNursery`` semantics to be more similar to
``trio`` in the sense that parent task errors are always packed into the
actor-nursery emitted exception group and adjusted all tests and
examples accordingly.

.. _pep 654: https://peps.python.org/pep-0654/#handling-exception-groups
.. _exceptiongroup: https://github.com/python-trio/exceptiongroup
