API: new kwarg for return raw response

[bsipocz]

Historically we had duplicated method names with "async" that would return the response rather than a parsed astropy Table.

We agreed to clear this behaviour up (e.g. #2598), but it also came up that having an easier access to the raw response can be useful (e.g. see the discussion in #3359).

So this is a formal issue to make the latter happen, we should add a return_raw_response or similarly named kwarg to the API rather than duplicating methods.

Let's brainstorm the kwarg first and then I recommend doing the API changes incrementally by adding the kwarg and in the same time removing the usage of the duplicating decorator.

[keflavich]

return_raw_response seems, at first blush, to be descriptive and adequately concise. But let's see if others who have been involved in these discussions want to chime in.

[bsipocz]

Yes, I certainly don't want to rush API decisions and refactorings.