[libbeat?, filebeat] Kafka Input: Add support for SASL authentication

[benqua]

Describe the enhancement:
Kafka input doesn't support SASL, while the support has been added to the kafka output (see #8387 ) .
It would be great to have SASL support in Kafka (filebeat) input.
For example the kafka service from AWS, AWS MSK, only support SSL auth or SASL/SCRAM-SHA512. Supporting this scheme would make it possible to read from AWS MSK with filebeat.

Describe a specific use case for the enhancement or feature:
We use filebeat to collect EKS logs, send them to MSK, read them back with filebeat to finally index them in the Elastic Cloud service.

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[benqua]

Any plan to support sasl kafka input?

[pchheda-lyft]

We need this as well for filebeat. Any plan to support this @jsoriano ?

[benqua]

Somehow related to #26294.
Any reaction from the maintainers of the project?

By the way, the fact that kafka input and output don't support the same set of feature is quite confusing.

[benqua]

Hi beat team, any plan to support sasl for kafka input?

[botelastic]

Hi!
We just realized that we haven't looked into this issue in a while. We're sorry!

We're labeling this issue as Stale to make it hit our filters and make sure we get back to it as soon as possible. In the meantime, it'd be extremely helpful if you could take a look at it as well and confirm its relevance. A simple comment with a nice emoji will be enough :+1.
Thank you for your contribution!