Added CallbackPositionProperty

[jfayot]

Description

This is a proposal for a CallbackPositionProperty, without making TS expose Property types as generics as mentioned here

Issue number and link

• CallbackProperty and positions #8944
• CallbackPositionProperty #5534
• CallbackPositionProperty #2597

Testing plan

Added specific spec file with 100% coverage on the CallbackPositionProperty class.
Updated PathVizualizer spec file to allow CallbackPositionProperty sub-sampling.
Added a specific sandcastle demo.

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @jfayot!

✅ We can confirm we have a CLA on file for you.

[ggetz]

Thanks @jfayot!

We'll review this shortly, likely early next week. If we merge, it will go into the October 1 release.

[jfayot]

This is ready 👀

[ggetz]

Thank you for your patience @jfayot! I will be able to do a full review tomorrow.

[ggetz]

This looks great @jfayot! And this is a fantastic Sandcastle example too!

A few small comments, but otherwise the code is looking great. Thanks again for the PR!

[jfayot]

Thanks for the review @ggetz ! Updated according to your comments. Should I resolve conflicts ?

[jfayot]

Resolved conflicts, should be ready to merge, but you'd better double check, I'm not a git expert...

[ggetz]

Looks great! Thanks again @jfayot!