Typescript rewrite

[jamiehaywood]

This is a first pass at rewriting the whole library in TS.

If you want immediate utility out of this PR, you could cherry pick commit 59e19b0 which has 90% of all the type declarations in a types folder which mirror the existing JS structure. All you would need to do is add a "types" key to the package.json file and point at the types folder.

Otherwise, things still TODO:

• rewrite exchange-code-for-token.js (w/ accompanying .d.ts file
• rewrite get-auth-urls.js (w/ accompanying .d.ts file
• rewrite tokens.js (w/ accompanying .d.ts file
• Add Prettier
• Add Husky v7
• Iron out the build step to compile from TS (probably use rollup to make a ESM export as well)
• rewrite tests to use jest
• Add better return types for the requests (instead of Promise<unknown>)
• Add eslint with TS configuration
• Fix spelling mistakes in package.json

[davidgtonge]

Wow, thanks @jamiehaywood

[ozamarripa]

This looks pretty good!
Out of curiosity, how come you changed the test to use Jest?

[jamiehaywood]

@ozamarripa a couple of reasons for picking Jest, but the main ones are:

• It has more weekly downloads on NPM
• It has got more out of the box (less setup and extra stuff to maintain)
• Syntax is nicer/clearer in Jest (subjective, but that's my feeling)
• Coverage reporting out of the box (again, if you're not looking at coverage then it's a non point, but it can be useful)
• Parallel test running