--[Part 2 of 2] Semantic region building

[jturner65]

Motivation and Context

This PR uses the Semantic Attributes introduced in this PR to build the Semantic Scene, including any region annotations, which are used to construct SemanticRegions.

How Has This Been Tested

Current c++ and python tests pass

Types of changes

• [ ] Docs change / refactoring / dependency upgrade
• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have completed my CLA (see CONTRIBUTING)
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.