server : implement json-schema-to-grammar.mjs & add grammar param in the UI

[jhen0409]

This PR implements json-schema-to-grammar.mjs by followed the Python implementation, it can be used in Web & Node.js.

I'm looking for a simple way to use JSON schema and gbnf, but I'm mostly using JS not Python for both client or server, so I thought it might be possible to have a JS implementation here, it should help others too.

Demo

Use a json schema as functions.json (From PR #2532):

{
  "oneOf": [
    {
      "type": "object",
      "properties": {
        "function": {"const": "create_event"},
        "arguments": {
          "type": "object",
          "properties": {
            "title": {"type": "string"},
            "date": {"type": "string"},
            "time": {"type": "string"}
          }
        }
      }
    },
    {
      "type": "object",
      "properties": {
        "function": {"const": "image_search"},
        "arguments": {
          "type": "object",
          "properties": {
            "query": {"type": "string"}
          }
        }
      }
    }
  ]
}

Usage in Node.js:

node chat.mjs --grammar-json-schema functions.json --grammar-json-schema-prop-order function,arguments
> Find an image of a dog.
{ "function" : "image_search", "arguments": { "query": "dog" }} 
> Schedule a birthday party on Aug 14th 2023 at 8pm.
{ "function" : "create_event", "arguments": { "date": "Aug 14th 2023", "time": "8pm", "title": "Birthday Party" }} 
> 

Usage in the UI, we can just use gbnf or put JSON schema and press the convert button:

Completions

[x4080]

This is very useful for integrating llama and traditional programming

[ejones]

Nice conversion! Code looks good.