Migrate to typescript with named exports

[rexxars]

👋 Hi Thomas!

We're revamping autofoos, and since we're now writing it in typescript, I thought it would be nice if accolade was using it too so we get some slightly better type safety :)

Apologies for this big PR - wish there was less tooling needed for typescript + testing.

Anyway, main gist of this is:

• Use jest instead of mocha (because it does better with typescript)
• Use typescript preset for babel (and specify ie11 as lower barrier for browser support)
• Add license file since it was missing
• Change API to use named exports (it's just easier to work with across ESM, CommonJS and TypeScript)
• Add typescript types
• Run prettier on codebase
• Use microbundle for bundling it
• Mark the package as being free of side-effects, for better tree shaking
• Run tests on GitHub actions as a CI

Let me know what you think!