WithCommonClient installs a backend.B into the supplied Context that loads its configuration from base.
Provider is a client.Provider that is backed by a config interface. This differs from client.RemoteProvider in that it takes an arbitrary config interface instance rather than generating a remote one.
Its intended use is for testing setups.
Provider performs access checks locally using access.CheckAccess.
GetConfigClient implements ClientProvider.
GetServiceURL implements ClientProvider.