EmbeddedEngine should allow for more flexible record consumption

Currently, the EmbeddedEngine exposes an API where the records can only be consumed a record at a time and the committing and flushing of records cannot be controlled by the user.

This effectively eliminates the possibility to do batching APIs or to have more advanced control over committing of records like in the case of async API.

By exposing a new interface that would give batches of records as well as the ability to control when to inform debezium that those records are committed, many more options are available.