Add support for importing JSON files

[zebfross]

This change adds support for importing JSON files using Langchain's JSONLoader. Here are the major changes:

• Created new routes and types in the backend-server
• Added appropriate frontend views
• Added HandleJsonDataSource.php that handles the uploaded files. Along with json files, I also allow zip files to be uploaded. Zip support required adding the "zip" php extension to the docker file.
• Added jsonHandler.ts to the llm-server that imports the json files. It uses Langchain's JSONLoader to import the files as documents.

[gharbat]

Wow!

Thanks for the amazing contribution! Will take a look at it tonight.

[inluxc]

How is this coming? I would love to load products list.