OIDC support should be on a per-vhost basis

[youngnick]

Please describe the problem you have
[A clear, concise, description of the problem you are facing. What is the problem that feature X would solve for you?]
The OIDC support implemented in #13 sets the same config for all vhosts serviced by the authserver installation.

We should consider making it so that the config can be different on a per-vhost basis.

[UXabre]

Hi, could somebody help me with how to pass any metadata via the virtual host? I know this hasn't been implemented for the OIDC part but I'm not sure if it is supported to pass any metadata at all? Just to be clear, i'm talking GRPC metadata.

EDIT: yeah... could've searched longer. I'm actually using authPolicy.context to pass any data to my auth backend.