From what was originall the `.devx._debug` monolith module, since that
file was way out of ctl in terms of LoC!
New modules so far include,
- ._repl: our `pdb[p]` ext type/lowlevel-APIs and `mk_pdb()` factory.
- ._sigint: just our REPL-interaction shield-handler.
- ._tty_lock: containing all the root-actor TTY mutex machinery
including the `Lock`/`DebugStatus` primitives/APIs as well as the
inter-tree IPC context eps:
* the server-side `lock_stdio_for_peer()` which pairs with the,
* client-(subactor)-side `request_root_stdio_lock()` via the,
* pld-msg-spec of `LockStatus/LockRelease`.
AND the `any_connected_locker_child()` predicate.
Tyler Goodlet