Data ingestion from Flink to Druid

### Motivation

We observe various applications utilizing the architecture of Flink -> Kafka -> Druid. However, in many cases, I believe that the Kafka hop may not be necessary. If a Flink connector for Druid were available, it would streamline the integration and make utilizing Druid much more straightforward

### Proposed changes

Open for discussion on implementation and code changes.

The issue names no files, tests, or entry points. Start by clarifying the proposed Flink-to-Druid connector scope, supported integration path, and expected behavior with the maintainers. Done would require an agreed design and implementation plan before code changes can be scoped.

Written by the indexing model from the issue text.