PE-41 Postoffice: Add support for Session - Private Messenger

[jpage4500]

For the Reviewer

• Code review complete
• Testing Complete
• Quality ORT App Documentation Updated (your name is in the Validator square for this feature)

When this is complete, you should approve the PR via github.

For the Reviewee

Summary

Description of changes.

Release Note

Required.

Breaking Changes

<Description for Techops of how to handle changes, migrations, updates>None.

Quality Assurance

You have gathered the following items:

• This PR is tagged with a Release Milestone
• You have a log message clearly identifying when this feature is working successfully
• You have a log message clearly identifying when this feature is failing
• You added a PR against p4-alerting to trigger based on the failure condition above

Given all of the items above, you have updated your Application ORT at the following locations:

• Features and Alerting: Required.
• P4 Alerting: Required.

Testing and Verification

Steps to test your application for someone not familiar with it. Required.

1. Do this: $ run-this.sh
2. Look for this.
3. Clean up with this command

[baracudda]

LGTM