Add findTags query param to /schemas & /subjects endpoints

[jsingh-yelp]

Hello team,

Description
Currently, the Core Schema Registry REST API does not support filtering schemas or subjects by tag. To find resources with a specific tag (e.g., PII, Deprecated), a client must currently fetch all subjects and versions to inspect their tags individually.

Solution

• I propose adding a query parameter to the existing listing endpoints to allow for server-side filtering by tag. Similar query params exists but for specific version: https://github.com/confluentinc/schema-registry/blob/master/core/generated/swagger-ui/schema-registry-api-spec.yaml#L1078. And purpose extending to other endpoints as follows:
  • GET /subjects?tags=PII
  • GET /schemas?tags=PII
• There is also the alternative to only add the above only at client lib level.