Update API definitions to fix CAMARA validation warnings #39

Problem description
CAMARA validation is giving warnings and hints for current definition
see: https://github.com/camaraproject/ApplicationEndpointRegistration/actions/runs/28826927101

Expected behavior
Update definition to remove warnings, and as many hints as required

Alternative solution
None

Additional context
Some warnings can be fixed using $refs to common schema files in code/common/