Error processor

[lovromazgon]

Description

Implements an error processor, that acts similar to the filter processor, only that it negatively acknowledges all records passed to it. This allows the user to stop the pipeline (or send records to the DLQ) if a record matches a certain condition.

I realized we need this when we updated the webhook processor to not fail on HTTP statuses less than 500. If a user wants to still configure the pipeline to fail if the status code is for example 404, they can configure an error processor now, e.g.:

version: 2.2
pipelines:
  - id: example
    status: running
    connectors:
      ...
    processors:
      - id: request
        plugin: webhook.http
        settings:
          response.status: '.Metadata["http_status"]'
      - id: fail-on-404
        plugin: error
        condition: `{{ eq .Metadata.http_status "404" }}`

[!IMPORTANT] ~Depends on https://github.com/ConduitIO/conduit-processor-sdk/pull/46, validate action will fail until we merge that PR and update the processor-sdk dependency.~ Updated.

Quick checks:

• [X] I have followed the Code Guidelines.
• [X] There is no other pull request for the same update/change.
• [X] I have written unit tests.
• [X] I have made sure that the PR is of reasonable size and can be easily reviewed.

[lovromazgon]

@raulb a blog post would be nice, feel free to take the initiative on that one, I'm kinda swamped right now.