Improve CreateRepositoryAttribute error messages

[Magnus-Kuhn]

Readiness checklist

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

Description

Validates attribute contents in the CreateRepositoryAttribute use case with serval instead of the ajv schema validator. Includes added tests with the resulting error messages when validations fail. It's not perfect (you can have additional properties and the errors of complex attributes are also unclear).
It's not clear that this approach is more promising than attempting to improve the ajv usage.

[codecov]

Codecov Report

Attention: Patch coverage is 63.82979% with 17 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...onsumption/attributes/CreateRepositoryAttribute.ts	63.04%	17 Missing ⚠️

Files with missing lines	Coverage Δ
...nsumption/src/consumption/ConsumptionCoreErrors.ts	80.90% <100.00%> (ø)
packages/runtime/src/useCases/common/Schemas.ts	100.00% <ø> (ø)
...onsumption/attributes/CreateRepositoryAttribute.ts	81.30% <63.04%> (-15.76%)	⬇️