KIP-465 — Add Consolidated Connector Endpoint to Connect REST API

Accepted Kafka 2.3 Connect

Adds `?expand=status` and `?expand=info` query parameters to the `GET /connectors` REST endpoint so clients can retrieve connector status and/or configuration for all connectors in a single request. Without this, fetching the status of N connectors requires N+1 HTTP calls (`GET /connectors` to list names, then `GET /connectors/{name}/status` for each), causing O(N) latency at scale.

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