Add critical operation signaling mechanism

[FelixTing]

🚀 Feature Request

Relevant Package [REQUIRED]

This feature request is for messaging client

Description [REQUIRED]

In the current go-mod-bootstrap, when a SIGTERM signal is received, the context cancel function is invoked, which immediately terminates message subscriptions and closes the message client connection. This can potentially interrupt critical operations that are still in progress.

Describe the solution you'd like

1. Allow messaging client to signal when critical operations begin and complete.
2. Provide a method to wait for critical operations to complete when necessary, such as during shutdown.