Is your feature request related to a problem? Please describe.

Following the discussion in #9870, the issue author noticed that SentenceWindowRetriever could support run_async by using the document_store.filter_documents_async method. A developer pointed out that this also applies to FilterRetriever and AutoMergingRetriever, and asked the community to open a PR if it's needed.

Describe the solution you'd like

Add run_async methods to both FilterRetriever and AutoMergingRetriever that rely on document_store.filter_documents_async.

For FilterRetriever, this should be straightforward since the main operation is document store filtering.

Regarding AutoMergingRetriever, I don't have first-hand experience with this component, but I expect the fix to be similar.

Describe alternatives you've considered

None, alternatives were already discussed in the original issue.

Additional context

• I can work on the PR