feat: adds `x-trestle-add-props` to the YAML header in SSP markdown

[jpower432]

Types of changes

• [ ] Hot fix (emergency fix and release)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [X] Documentation (change which affects the documentation site)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Release (develop -> main)

Quality assurance (all should be covered).

• [ ] My code follows the code style of this project.
• [X] Documentation for my change is up to date?
• [X] My PR meets testing requirements.
• [X] All new and existing tests passed.
• [X] All commits are signed-off.

Summary

Reuses logic from profile markdown generation with x-trestle-add-props in SSP markdown.

Closes #1524

Key links:

• Sonar coverage

Before you merge

• Ensure it is a 'squash commit' if not a release.
• Ensure CI is currently passing
• Check sonar. If you are working for a fork a maintainer will reach out, if required.

[jpower432]

@vikas-agarwal76 @AleJo2995 Planning to keep this in draft until features are accepted and will rework as needed. Wanted to share the approach earlier though.