Bug 1682364 - Add missing fields to Messaging System schema

[ncloudioj]

Checklist for reviewer:

• Commits should reference a bug or github issue, if relevant (if a bug is referenced, the pull request should include the bug number in the title)
• If adding a new field, the field should have a description (see Bug 1652842 - Add a blocklist field so the environment schema works with pre- and post-bug-1647225 data #576 for an example)
• Scan the PR and verify that no changes (particularly to .circleci/config.yml) will cause environment variables (particularly credentials) to be exposed in test logs
• If the PR comes from a fork, trigger the integration CI test by pushing this revision as discussed in the README and review the report posted in the comments.

For glean changes:

• Update templates/include/glean/CHANGELOG.md

This adds two missing fields to the Messaging System schema as described in this comment.