Add Support for Request Queueing and Custom Queue Behavior

[uezo]

Currently, when a new request is received while another request is being processed, the ongoing request is interrupted, and the new request is processed immediately. However, this behavior may not be desirable in all situations, especially when handling requests from external programs.

Request:

• Implement a queueing system for incoming requests.
• Allow ongoing requests to complete before processing new ones, based on user-defined preferences.

Additionally, it would be beneficial to support the following features:

• Ability to perform custom actions at the time a request is queued.
• Option to hide the UserMessageWindow when start processing the new dequeued request.

This functionality would greatly improve flexibility in handling multiple requests and allow for better control over the request flow, especially when integrating with external systems.