KAFKA-20366: Add syntax highlighting in security docs

[gomudayya]

• Added syntax highlighting to code blocks in the Security and Streams sections.
• Updated authentication-using-sasl.md by adding line-continuation characters and refining indentation for better readability.
• Built kafka-site locally to verify the changes and manually checked each affected page.
• This is a follow-up PR to previous work (KAFKA-20050: Add syntax highlighting for code blocks and commands #21845, KAFKA-20366: Add syntax highlighting across docs, excluding security and streams #21887). With this change, the syntax highlighting across all relevant documentation pages is now completed.

[mimaison]

Thanks for the PR. I left a couple of comments

[mimaison]

Is there any value in setting the language to test?

[gomudayya]

It's to enable the copy icon, and to keep it consistently handled by Hugo's code block render hook.

[mimaison]

Is properties the correct language? According to https://gohugo.io/content-management/syntax-highlighting/#languages I see it called java-properties

[gomudayya]

When I built the Kafka website locally, it rendered with highlighting, so I didn't notice the issue.
As you pointed out, java-properties is the officially documented identifier in Hugo, so I'll update it accordingly.

[mimaison]

I'd recommend doing it one folder at a time. It does not make a lot of sense to do Streams and Security in the same PR.

[gomudayya]

I'd recommend doing it one folder at a time. It does not make a lot of sense to do Streams and Security in the same PR.

Agreed. I'll revert the Streams changes from this PR and update the title and description accordingly. I'll open a separate PR for Streams afterward. Thanks for the review!

[mimaison]

LGTM