Implement and test ordering in observable:MessageThread

[ajnelson-nist]

This Pull Request resolves all requirements of Issue 393.

Review steps taken:

• [x] Pull request is against correct branch
• [x] CI passes in (CASE/UCO) feature branch
• [x] CI passes in (CASE/UCO) current unstable branch (merge-commit)
• [x] Impact on SHACL validation reviewed for CASE-Examples
• [x] Impact on SHACL validation remediated for CASE-Examples
• [x] Impact on SHACL validation reviewed for casework.github.io
• [x] Impact on SHACL validation remediated for casework.github.io (N/A)
• [x] Demonstrate usage in CASE-Examples JSON files
  • [x] message.json updated in this PR
• [x] Solution vote today incorporates that observable:message should be removed from observable:MessageFacet, and also removed from the ontology.