feat: additional graph commands, extra graph codegen tests, and type definitions

[sgrove]

Summary

Continuing to polish the graph experience, and as things start to solidify (we're changing the generated code style much less frequently now) adding in some snapshot tests to make maintenance easier.

(Probable) Bug fix:

Incorporates @ehmicky's suggestion to handle filenames with spaces in them here

Codebase improvements:

Fixes some codegen failures, and adds a test matrix to keep track of the outputs of various flag combinations as well
Adds some type definitions (I didn't know about // @ts-check, quite helpful!)

To make the Graph DX completely usable from the CLI (no web GUI):

Adds a graph:library command to generate the function library based on the operation file
Adds a graph:handler command to generate a handler via the operation name locally (makes the UI optional for the normal flow)
Adds a graph:operations command to list the operations available in the local library

---

For us to review and ship your PR efficiently, please perform the following steps:

• Update or add tests (if any source code was changed or added) 🧪
• Update or add documentation (if features were changed or added) 📝
• Make sure the status checks below are successful ✅

[sgrove]

Failing tests seem to be related to #3948