Allow users to directly pass on options to the API call (e.g., via '...' and req_options)

[yannikbuhl]

At the moment, most of restatis's functions do not allow to modify the underlying HTTP call using httr2. For example, this might be a problem once someone tries to add proxy information. In httr2 it seems that there is no other way than using req_options to add more options to the API call. This is, at this moment, not supported by restatis and could be considered being added to all functions.

[yannikbuhl]

We would need to have the ... passed on to httr2::req_options(...) so you can set a proxy, for example.

[yannikbuhl]

This would generally work but the question remains as to what to do with functions that use ... to pass additional parameters to the API call...