fix: resolving typing issues in JS codegen

[erunion]

🚥 Fixes #588

🧰 Changes

• Update codegen for CJS exports to have the main createSDK export set as export = in the .d.ts file. Having it as export default createSDK was causing issues where the typing was expecting you to to do sdk.default.someOperation even though the way you load the SDK doesn't require you to have to destructure it off default.
• This also updates JS type generation to no longer export types in the main SDK entry point as it's causing issues with the affformentioned default export issue and also JS users can't import these types anyways. They'll still have access to them by way of TS intellisense but if you want to import these types you'll obviously need to use TS codegen or load them from types.d.ts. And yes this does work even though the file has a .d.ts extension:

🧬 QA & Testing

This is what using a CJS SDK looks like now:

What it looked like before (with export default createSDK in the index.d.ts file):

[erunion]

Ignore the smoketest failures, the dataset from https://api.apis.guru seems to delete specs when they get version bumps and we run with a local copy of https://api.apis.guru/v2/list.json

[kanadgupta]

other than the small comment suggestions, LGTM!