Add Argilla integration

[sdiazlor]

This is a Haystack integration with Argilla for Haystack 1.x as discussed in https://github.com/deepset-ai/haystack-integrations/issues/25. We use Agents to monitor the data and allow the annotation in the Argilla platform.

Due to some limitations of Haystack 2.0, we plan to do a refactoring when callbacks/Agents become available (instead of using now the chat endpoints for some available models).

[sdiazlor]

@annthurium Due to some small changes, this is an integration that continues the work of my colleague here. Please could you review it as a Haystack 1.x integration and close the previous PR?

[annthurium]

@sdiazlor thanks for your submission! The Haystack team doesn't currently have bandwidth to review 1.x integrations, since we're getting close to the 2.0 GA release. We'll get back to you after that. Sorry about that.

[TuanaCelik]

Spoke with David Berenstein and we will wait on this until 2.0 is supported.