feat: Integrate MessagingClient critical operation signaling into shutdown process

[FelixTing]

fix: #896

This enables service to wait for MessagingClient critical operations to complete during graceful shutdown.

This depends on edgexfoundry/go-mod-messaging#436

PR Checklist

Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added unit tests for the new feature or bug fix (if not, why?)
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• I have opened a PR for the related docs change (if not, why?)

Testing Instructions

[cloudxxx8]

LGTM