KIP-1365 — Transform Observability and Skipped Record Handling for Kafka Connect

Discussion ConnectMetrics

Adds per-transform operational metrics (record counts, throughput, error attribution) to the Kafka Connect SMT chain and a mechanism to inform sink connectors about records dropped or diverted before delivery. The `connector-transform-metrics` group exposes only static class name and version, so operators cannot tell how many records a filter drops or which transform in a chain is failing, and sink connectors see offset gaps for records they never received.

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