Build IDL JSON parsing & type conversion for JavaScript SDK

[buffalojoec]

We need to start building out the JavaScript SDK.

At the time of writing this issue, the JS SDK currently has a skeleton for initializing a Nautilus instance and parsing SQL query strings.

Some of the skeleton shows how we can build this SDK, but I am open to proposed changes.

Problem:
The first step in the JavaScript SDK is going to be to take an IDL as input and create a TypeScript version of our program - similar to Anchor and Solita.

We can investigate using Anchor, Solita, or another existing tool to power this functionality, however I have the following requests:

• No additional configuration files (ie. .solitarc, Anchor.toml)
• No CLI commands (ie. shank, solita)

We may also choose to write this functionality ourselves, and since JSON is closely related to JavaScript, this may not be too awful to do.

One thing worth mentioning: the Rust crate for the IDL currently has a POC build for converting JSON to TypeScript. We may decide that's an easier route to take rather than trying to import a JSON file to the SDK's Nautilus instance.

---

I encourage draft PRs and Proof-of-Concepts