Publish TypeScript types for this package

[blimmer]

Self-explanatory. It'd be nice to have types delivered natively with this package, but we could also go the DefinitelyTyped route, as well.

[mbklein]

@blimmer I've taken a stab at adding the appropriate .d.ts files. VS Code's Intellisense is picking up the types nicely in my tests, but since I'm a bit new at combining JS code and TS types in a single package, would you mind referencing the branch from a project and seeing if it's behaving as you'd expect?

"dependencies": {
  "iiif-processor": "github:samvera/node-iiif#35-add-typescript-types"
}

[blimmer]

Thanks! Looking good so far. I tried this on a repo using this package and found only one issue with the streamResolver.