Add Kotlin Language Support for Classes Structure (#728)

[naeem4633]

Changes done to meta_info.json

• Added Kotlin folder.

What GitHub issue does this PR apply to?

Resolves #728

What changed and why?

• Added a new folder named kotlin inside the web/thesauruses directory.
• Created a subfolder 1.5 within the kotlin directory to represent Kotlin version 1.5.
• Added a classes.json file inside the kotlin/1.5 directory containing the necessary content to define various class concepts in Kotlin.
• Updated the meta_info.json file to include an entry for Kotlin and to ensure that the "Classes" structure is recognized for Kotlin.

(If editing website code) Please add screenshots

• Not applicable.

Checklist

• [x] I claimed any associated issue(s) and they are not someone else's
• [x] I have looked at documentation to ensure I made any revisions correctly
• [x] I tested my changes locally to ensure they work
• [x] For language files, I have validated the edited files are valid JSON and data shows up correctly
• [x] For website code edits, I have added or edited any appropriate unit tests for my changes

Any additional comments or things to be aware of while reviewing?

• None.