They are now deprecated, and swh-storage ignores them, so it caused tests to fail.

The error raised from keycloak can be less detailed than anticipated [1]. This makes the
deposit server fails. So this commit fixes it by detailing only if it can. Delegating
such details to the newly crafted swh.auth.keycloak.keycloak_error_message utility.

[1] https://forge.softwareheritage.org/differential/revision/edit/5311/

Related to T3166

The error message in case of authentication failure is now aligned with the previous
basic authentication scheme. Prior to this, the keycloak error dict leaked into the
summary field which made the error unreadable.

Related to T2858

This reworks the internal authentication mechanism to delegate that part to keycloak.
Through a Direct Grant access flow.

It's transparent for the deposit clients. They will continue their authentication
against the deposit server. Internally, the deposit server will require authentication
on their behalf.

Related to T2858

This is what the current code inlined is doing already. This code was anterior
to the function being born in swh.core.config

It is deprecated since model 0.3.8.

Related to D3419

This also ensures the loader sends all the required information now (it did
already but it was a bit laxed on checks for that part).

Related to T2398

This later no longer exists.

It no longer needs that argument.

'swh' being the new master command group (defined in swh.core); so:

  swh deposit --help

works. The 'admin' (deposit server management) is only available if the
swh.deposit[server] optional package is installed.

Ensure the 'swh-deposit' still works for now.

Related T1034

Related T565

Related T335
Related T933

Related T871

swh-core, swh-loader-tar

Related T857

Goal: Reducing dependencies

The actual dependency to the current code does not depend on the
latest yet.