[BUG] Missing Configuration details in Kafka documentation

[cmanning09]

Describe the bug
Kafka ReadMe does not detail configuration options like:

1. broker_configuration_type
2. aws_msk_iam
3. ssl_endpoint_identification_algorithm
4. AwsIamAuthConfig.role
5. key_mode

This is not an inclusive list. I only looked through a handful of configuration options and found these. There may be others.

Additional context
Documentation Website is lacking details as well. It has some of these but is missing some as well and needs to be thoroughly reviewed.

[cmanning09]

There are no details for metrics provided by the Kafka Source plugin in either ReadMe

[dlvenable]

These details should go into the documentation and we'll want to avoid duplication in the README.

[dlvenable]

I moved this to the 2.5 release. Let's clean up the README.md and make sure that the documentation has the correct information.

[sandervandegeijn]

Also the configuration details are different between the docs and the test files.

https://opensearch.org/docs/latest/data-prepper/pipelines/configuration/sources/kafka/ look at the encryption entry.

This differs from
https://github.com/opensearch-project/data-prepper/blob/main/data-prepper-plugins/kafka-plugins/src/test/resources/sample-pipelines.yaml

Correct config:

[kkondaka]

broker_configuration_type, aws_msk_iam and key_mode are documented. aws_msk_iam: "role" is also documented. ssl_endpoint_identification_algorithm is not applicable to kafka source. It should be documented when kafka sink is made available