Enforce unique array items

[Magnus-Kuhn]

Readiness checklist

• I added/updated tests.
• I ensured that the PR title is good enough for the changelog.
• I labeled the PR.
• I self-reviewed the PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
packages/content/src/attributes/IQLQuery.ts	94.20% <100.00%> (+0.26%)	⬆️
...ckages/content/src/attributes/IdentityAttribute.ts	88.70% <100.00%> (+0.57%)	⬆️
...s/content/src/attributes/IdentityAttributeQuery.ts	88.88% <100.00%> (+0.55%)	⬆️
...attributes/ThirdPartyRelationshipAttributeQuery.ts	100.00% <100.00%> (ø)
...ackages/content/src/attributes/hints/ValueHints.ts	98.68% <100.00%> (+0.02%)	⬆️
packages/content/src/requests/Request.ts	100.00% <100.00%> (ø)
packages/content/src/requests/RequestItemGroup.ts	97.77% <100.00%> (+0.05%)	⬆️
...sts/items/formField/FormFieldAcceptResponseItem.ts	94.87% <100.00%> (+0.42%)	⬆️
...s/formField/settings/SelectionFormFieldSettings.ts	45.63% <100.00%> (+1.63%)	⬆️
packages/runtime/src/useCases/common/Schemas.ts	100.00% <100.00%> (ø)
... and 5 more

... and 9 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.