Fix/gr ndsp 125 duplicate keys in data contract details

[georgeRobertson]

TLDR of changes

Issue with defining different details for columns that have the same name across entities. Changed the structure of the data contract details to specify entity name as the first key and then columns afterwards.

What kind of changes does this PR introduce?

Tick all that apply

• fix: A bug fix. Correlates with PATCH in SemVer
• feat: A new feature. Correlates with MINOR in SemVer
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
• refactor: A code change that neither fixes a bug nor adds a feature
• perf: A code change that improves performance
• test: Adding missing or correcting existing tests
• build: Changes that affect the build system or external dependencies (example scopes: pip, docker, npm)
• ci: Changes to CI configuration files and scripts (example scopes: GitLabCI)

Please check if the PR fulfills these requirements

• I have read and followed the Contributing guidance
• Docs have been added / updated
• Tests and Linting in the CI are passing
• Changes have been reviewed and approved by a Project Maintainer

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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