Refactor fdpApi and add fetchUtils

[dennisvang]

This moves the bindOperation calls to fdpApi.ts to improve cohesion.

Also moved the generic request and fetch* functions from fdpApi into a separate fetchUtils module to prevent circular imports between apiDocs and fdpApi, and renamed fetchApiDocs to fetchJSON.

@mihailefter these are just some quick-and-dirty changes to illustrate what I had in mind in my review of #64

Feel free to ignore, or modify to your liking. 🙂

todo:

• fix circular imports (fdpApi now imports from apiDocs, which imports from fdpApi, ...) -> perhaps move the fetchRdfTurtle, fetchApiDocs and related functions into a separate module?

[mihailefter]

Hi @dennisvang! This is a real improvement, thanks. I pushed a few small changes on top: converted searchResources too, since it was the last function still taking url and method, added some tests, and updated some stale comments in the tests.

I’ll squash and merge this entire stack now to complete this and close the corresponding issue, if you agree.

[dennisvang]

Hi @mihailefter well spotted, somehow I missed that searchResources. 😅

Yes, please, go ahead with the merge (this will close #34 automatically).