[define] evaluate proposed w3c standard "Content Negotiation by Profile"

[BirgitBader]

(i) This issue has been manually transferred from a former internal repository, as a private repository issue cannot be transferred to a public repository.

Context

W3C proposed a standard to use profiles in content negotiation: https://w3c.github.io/dx-connegp/connegp/

It differs from the way we use profiles. Instead of using the profile as a media type parameter, it is used as a separate header Accept-Profile and Content-Profile in content negotiation.

Depending on the outcome of https://github.com/w3c/dx-connegp/issues/41, we should evaluate if it makes sense to adapt to the w3c proposal.