initial work on generating JSON (de)serialization + .ts types from it
so that we can get better type information than simply `any` in the .ts/flow type annotations. This is a multi-phase process: 1) Generate (using `schemars` traits) .json schemas for all types. This is done by running the program in rust/json-gen which will export these to rust/json-gen/schemas 2) Running scripts/run-json2ts.js to convert these to .ts files 3) We will need to convert the names to add in the JSON suffix to these (not implemented yet) 4) Running scripts/json-ts-types.js to replace any `any` return types with the correct *JSON type generated above some files are hardcoded so they don't line up right now and some steps aren't working as the schemas generated in 1) inline ALL referenced schemas within a single schema so in step 2) we end up with a lot of duplicate type definitions. We might be able to just have a stage to remove duplicates from the schemas, or maybe there's a way to change the json to ts tool to not do that. Some types also throw runtime errors when serializing e.g. non-string keys despite compiling fine since serde != serde_json
