[FEATURE] support external kafka

[alondayan2]

Feature Description

Currently, only external Redis and PostgreSQL are supported, but adding support for external Kafka would be beneficial as well.

Possible Implementation

• Add support for passing credentials https://github.com/juspay/hyperswitch/blob/main/crates/router/src/services/kafka.rs#L300
• Add external kafka config to the helm chart https://github.com/juspay/hyperswitch-helm/blob/main/charts/incubator/hyperswitch-app/values.yaml#L820

Have you spent some time checking if this feature request has been raised before?

• I checked and didn't find a similar issue

Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

Are you willing to submit a PR?

Yes, I am willing to submit a PR!