Support PEM based certificates for SSL configuration in Kafka autoconfig

[frezelth]

Feature Description

Currently Kafka autoconfiguration supports loading certificates from a file, but does not support loading of a string based PEM certificates.

This possibility is supported in Spring Kafka using those properties:

• spring.kafka.producer.ssl.key-store-certificate-chain
• spring.kafka.producer.ssl.trust-store-certificates
• spring.kafka.producer.ssl.key-store-type
• spring.kafka.producer.ssl.trust-store-type

It's always possible to redefine the KafkaProducer bean but it would be great to have it supported out of the box!

Thanks

[smcvb]

Fair request, @frezelth!
Given the easy workaround and the team's schedule, I have set the priority to a 4 (lowest).

However, I think it's pretty straightforward to provide a pull request for this.
Hence, I have set the "Ideal for Contribution" label on this issue.

Thus, if you're up for the task, we'd be looking forward to a pull request!