Add inspect-ready-q and inspect-scheduled-q HTTP API endpoints

[edgarsendernet]

Having the ability to quickly see queue configuration would be very helpful when managing and tuning KumoMTA. Parameters:

• queue name
• limit (the number of message spool IDs to return, default 50)

Response would contain:

• configuration values (queue config or egress_path config)
• next delivery time (for scheduled queues)
• array of message spool IDs in the queue. These could be used to fetch message data from inspect-message endpoint.