fix: Configuration to be able to control sending RFC 9457 related Accept HTTP header

[cstamas]

Some servers have issues handling it (esp the Accept HTTP header), so make it possible to disable it. Moreover, the new config accepts REPO_ID suffix, so this can happen per-server basis.

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[kwin]

In addition we need to add Accept for regular content (either wildcard for all requests or xml/binary depending on whether it is metadata or artifacts) when we add the accept for problem+json

[kwin]

This is a confusing comment to me, as this is just about the accept header which is not actually specified in the RFC. I would therefore rather refer to it as EXPLICITLY_ACCEPT_PROBLEM_JSON

[cstamas]

This and @slawekjaranowski comment below makes sense, this config should be ONLY about Accept header, and then as Slawek says below, just always parse response?

[slawekjaranowski]

maybe we can always parse response?

[cstamas]

In addition we need to add Accept for regular content (either wildcard for all requests or xml/binary depending on whether it is metadata or artifacts) when we add the accept for problem+json

I find this problematic: adding xml or json or any other Accept is not right; transport is only about artifacts, and as we know, servers knows to be picky. So, ideally I'd just modific the text of this config param (it is ONLY about adding Accept to fully support RFC 9457), because historically Resolver never sent any Accept header at all.

[cstamas]

Also, in this very case, it just happens that we use a REST endpoint of an older software. Usually, Resolver transport is hitting non REST.

And this happens ONLY as nx2 offered "transparent support" for maven-deploy-plugin, while deployment to staging was always possible via alternate means (native plugin or so).

[kwin]

I would still add */* to accept header values (in case they are sent) but can be done in a separate PR.