relax validation for internal schema fragments
Problem: indexer schema (schema service) parsing validation has broken existing schema consumption, resulting in record not being indexed
Explanation: Kind schema can be composed of fragments. These fragments can be internal or external to a schema. Internal schema fragments are required to be defined on the schema ('definitions' block) whereas external fragments (e.g. AbstractFeatureCollection) can be registered separately with schema service. Schema service resolves these reference when a user makes request to kind schema.
External fragments follows fully qualified kind names: :::.., e.g. AbstractFeatureCollection will be registered: opendes:wks:AbstractFeatureCollection:1.0.0, whereas internal fragments do not have same requirements.
Recent indexer updates expects all references to have fully qualified names (internal or external). This MR relax the the validation thus enabling internal schema fragments parsing by indexer