feat: add studyType to StudyLocus and Colocalisation (and StudyLocusOverlap)

[vivienho]

✨ Context

studyType is needed to:

• Filter credible sets (StudyLocus) and Colocalisation results at the API level
• Influence the logic of which StudyLocus are compared in Colocalisation, derived from the StudyLocusOverlaps

See #3444 for more info.

🛠 What does this PR implement

studyType is added to StudyLocus.
rightStudyType is added toStudyLocusOverlap, and Colocalisation.

Changes were made to the schema, creation of these objects and tests involving these objects.
Code is updated in cases where getting the studyType/rightStudyType from the StudyIndex isn't required anymore.

🙈 Missing

🚦 Before submitting

• Do these changes cover one single feature (one change at a time)?
• Did you read the contributor guideline?
• Did you make sure to update the documentation with your changes?
• Did you make sure there is no commented out code in this PR?
• Did you follow conventional commits standards in PR title and commit messages?
• Did you make sure the branch is up-to-date with the dev branch?
• Did you write any new necessary tests?
• Did you make sure the changes pass local tests (make test)?
• Did you make sure the changes pass pre-commit rules (e.g poetry run pre-commit run --all-files)?

[DSuveges]

All really makes sense. Great job tracking down all the consequences of the change! I hope you found the breaking tests useful.