feature: cross-language parsing support for the server

it should be a standalone, runtime agnostic library that acts as a canonical reference implementation for reliably parsing various language ASTs across languages. if someone wants to add wide-reaching LSP/general AST support for a language, they would add it here. same with adding new template tag/other delimiter patterns.

the library should, given a content string and URI, be able to detect whether the extension is a supported language, and respond with an array of something like [this CachedContent type](https://graphiql-test.netlify.app/typedoc/modules/graphql_language_service_types.html#cachedcontent):

```ts

type CachedContent = {
range: Range,
content: string // raw embedded graphql string, don't need to parse this yet
}

type parseEmbeddedGraphQL = (content: string, uri: string) => Promise
```

we should use https://github.com/tree-sitter/tree-sitter as per many recommendations

we can use node.js or WASM bindings, for usage in language server at first, and monaco mode eventually.

we could also add this to graphql-config, to allow it to consume a wide range of languages performantly, and then be able to `project.loadDocuments()` across a wide range of languages