Conceptually we've been moving towards having our GPG verification
paths be per-remote. The code internally supports this, but we
didn't expose an API to use it conveniently.
This came up when trying to add a new `gpgkeypath` option, since
right now rpm-ostree manually finds keyrings for the remote, and
hence it wasn't looking at the keypath, and said "Unknown key"
in status.
Adding an API fixes this nicely.
Closes: #576
Approved by: giuseppe
Colin Walters
24bf257ee9