We believe this API is more forwards compatible with future secrets management
use cases. The implementation is a cry for help, but I was trying to follow the
previously established pattern of encapsulating the secret generation
functionality to a single group of packages.
This commit makes a breaking change to the current OIDCProvider API, but that
OIDCProvider API was added after the latest release, so it is technically still
in development until we release, and therefore we can continue to thrash on it.
I also took this opportunity to make some things private that didn't need to be
public.
Signed-off-by: Andrew Keesler <akeesler@vmware.com>
