Interface for making "raw" API calls

[janbuchar]

Possibly just a simple 1:1 mapping of CLI to API endpoints (i.e. ApifyClient methods) - e.g. apify apiCall dataset listItems. It may also be viable (as @vladfrangu suggested) to just accept URLs as the CLI argument.

The advantage of this would be that

1. it would handle authentication (as opposed to plain curl),
2. there would be a way to call every endpoint from the CLI, and
3. we may even have autocompletion one day