Avoid processing incoming bodies unnecessarily

[IvanUkhov]

Previously, I defined the body to be Full<Bytes>, which meant that the response would have to be fully received inside the API functions. However, that seems wasteful if one wants to do some streaming processing of the incoming data. This PR switches over to http_body_util::combinators::BoxBody, which is what is recommended in cases of having to accommodate different response types.

[Byron]

Thanks a lot for your help with this, it's much appreciated!

Now that it seems that CI caught a legitimate issue that is way too easily ignored, let's merge this PR only after the CLI related tests are in their own jobs so they can be expected to fail officially (I think CI can also be told so) so we are back at 'green CI by default'.

That should make further possibly even sweeping changes possible without adding unintended breakage.

[IvanUkhov]

Oh, was not paying attention to the CLIs. I will take a look.

[Byron]

The CLIs don't even get to fail as there is a legitimate failure elsewhere. Maybe it was previously introduced and nobody noticed, but either way, that just shows it's a problem to live with red CI. What I can live with is red CI for CLIs, once separate, but think that ideally it should then also be marked to allowed failure.

[IvanUkhov]

Yeah, I think that one is a legitimate failure that should be eliminated. If I had noticed, I would not have let it in.

[IvanUkhov]

I actually misread the error. It was not about the CLIs; it was about the APIs with the default features disabled. It should be resolved now.

[Byron]

Thanks a lot, it now looks like a 'good failure'.

Do I understand correctly that you are not interested in splitting the CI jobs between API and CLI to prevent such issues in future?

[IvanUkhov]

Sure! Let me do that.

[Byron]

Thanks again, particularly about the improvements to CI!
Now I am also curious if 'expects to fail' is something that CI can do, but then again, I still have hopes that the CLIs can be made to work or that those that aren't working can be excluded one day.