Acknowledgements support in Drop processor

Is your feature request related to a problem? Please describe.
Acknowledgements are not received by sources (such as S3/Kafka) if a pipeline has drop processor to conditionally drop events and has "acknowledgements" enabled.

Additional context
This was tested with following pipeline config. Kafka source did not receive acknowledgements for dropped events and did not commit offsets for consumed records.

version: "2"
kafka-pipeline:
  source:
    kafka:
      acknowledgments: true
      topics:
        - name: "test-drop"
          group_id: "Mac-group"
          serde_format: "json"
          auto_offset_reset: "earliest"
      aws:
        msk:
          arn: "arn:aws:kafka:us-west-2:388303208821:cluster/gameday-cluster/8cae81cb-3b38-4b59-8f47-cadee5a804f0-6"
          broker_connection_type: "public"
        sts_role_arn: "arn:aws:iam::388303208821:role/pipeline-to-domain-role"
        region: "us-west-2"
      authentication:
        sasl:
          aws_msk_iam: "role"
  buffer:
    bounded_blocking:
      batch_size: 125000
      buffer_size: 1000000
  processor:
    - grok:
        match:
          message: ['%{IPORHOST:clientip} \[%{HTTPDATE:timestamp}\] %{NUMBER:response_status:int}']
    - drop_events:
        drop_when: '/response_status >= 900'
  sink:
    - stdout:

Sample logs in kafka topic:

{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 400"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 300"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}
{"message": "127.0.0.1 198.126.12 [10/Oct/2000:13:55:36 -0700] 200"}

Start by tracing the drop_events processor and the acknowledgements path used by the Kafka source, using the pipeline configuration and sample records in this issue. Reproduce the case with acknowledgements enabled and verify that dropped events are acknowledged and consumed Kafka records have their offsets committed.