add dpl command for foreachBatch execution

[kortemik]

Description
add dpl command for enforced batch/driver execution. currently aggregations are processed in paralel mode which does not permit all the possible use cases that spark offers.

| teragrep exec foreachBatch [|transformStatements]

Use case or motivation behind the feature request
there are cases where the aggregation should happen only in sequential mode and forget the previous batch. such are when only batch-window aggregations are required like for example supporting a use case where trigger is configured for 5 minutes and the data between now and the last 5 minutes would be required to do the aggregation.

Related issues

Additional context