Improve documentation and code for 4CAT API calling

[sal-uva]

I just integrated a 4CAT data source search call in a local python script and lo and behold.. it worked great! But at the moment it's a bit of a forgotten child. We should really improve the documentation and (some of) the code on this, because it's an amazing feature.

Things to improve:

• Write documentation
  • How to retrieve an API key
  • What endpoints are available (queue-query, check-query, etc).
  • Have some kind of reference point for the options dictionaries per datasource and processors.
  • Scalar implementation?
• Make sure "-search" doesn't need to be removed for data source IDs.
• Set frontend-confirm to True by default.
• Remove some of the old code that still assumes we're searching for text for every data source.

[stijn-uva]

We have auto-generated documentation at /api/spec/tool/swagger.json (see also /api/) that addresses some of the points above. We could update it and use something like Scalar to generate pretty documentation with it...

[sal-uva]

That would be cool. And references on GitHub and 4cat.nl so people can actually find this option.