This is much nicer UX for an administrator installing a UpstreamOIDCProvider
CRD. They don't have to guess as hard at what the callback endpoint path should
be for their UpstreamOIDCProvider.
Signed-off-by: Andrew Keesler <akeesler@vmware.com>
Because we want it to implement an AuthcodeExchanger interface and
do it in a way that will be more unit test-friendly than the underlying
library that we intend to use inside its implementation.
Also move definition of our oauth client and the general fosite
configuration to a helper so we can use the same config to construct
the handler for both test and production code.
Signed-off-by: Ryan Richard <richardry@vmware.com>