Introducing ksqlDB

Introduces ksqlDB, a significant evolution of KSQL, by adding two major features: pull queries and connector management. Pull queries enable point-in-time lookups on materialized tables, complementing existing push queries (continuous streams of changes). Connector management allows direct control of Kafka Connectors within ksqlDB for data ingestion and export. This aims to simplify event streaming application architectures by reducing the number of distributed systems required.