Add queue inspection tools to the debug system.

[niACS]

Extend the existing debug system to report the number of items currently in an actor's queue, and to separately list the message names in an actor's queue.

Discussed in #144

^{Originally posted by CaseyZS October 29, 2025}
Is there a reason why it's not possible to view something like the Msg queue size? Being able to see if the queue is getting backed up is valuable information.

[niACS]

Here is my high level impression of the tasks required. This will need to be fleshed out before we can work it.

• Add a debug-only method to the Enqueuer class that returns another Message Queue protection proxy. This protection proxy only allows status queries. Note that these status queries must account for all four of the priority queues.
• Add a function to the debug functional global that will return the queue proxy for a given actor.

Actor Hierarchy Inspector is not yet a part of this open-source project, so enhancing it is technically out of our scope. But Neil or I can take on those enhancements in our private capacity.