[Kafka Trigger] Ease multiple topics consumption

[Giovannini]

Is there an existing issue for this?

• I have searched existing issues, it hasn't been reported yet

Use case description

The Serverless configuration for Kafka trigger only enables the consumption of a single topic per trigger. AWS already enables to reference multiple topics on a single trigger so this is not a technical limitation.

Proposed solution (optional)

The configuration parameters can be updated to load either a list of topics or a single topic and that list can be sent to AWS.

To keep compatibility with existing API (which uses topic singular), we may add a new field key and ensure that only one of the two is used. This could look like this:

events:
  - kafka:
      accessConfigurations: ...
      topics:
        - myTopic-1
        - myTopic-2
      consumerGroupId: ...
      bootstrapServers:
        - ...

[austencollins]

Thanks @Giovannini. We're looking into this now.