Mapping rules JSON V2

[AndrewThien]

✨ Feature

PR Description

This PR added the function to build version 2 of Mapper's mapping rules JSON (version 1 function is kept intact, only moved down to near the v2 function).
The structure changes are the main focus of this PR. It will help to solve the issue about value_as_concept_id (#1008) in the future.

Related Issues or other material

Closes #1142

[AndrewThien]

When you have time, can you double-test this one, please? @brian-kim31, if you haven't done so?
Please test (and compare to V1) using many scenarios and domains, etc.

[brian-kim31]

When you have time, can you double-test this one, please? @brian-kim31, if you haven't done so?
Please test (and compare to V1) using many scenarios and domains, etc.

Sure I'll test it

[brian-kim31]

@AndrewThien The new JSON format is much easier to work with. It organizes everything by source table, so you don’t have to repeat the same info over and over. Field and concept mappings are grouped in a way that’s cleaner and more logical, and it’s easier to see how source data connects to the final model. It also makes updates and future changes more straightforward, especially when handling larger datasets or multiple concepts in one go. Approved.