image: Attempt to resolve frontend from remote contexts
Previously the use of a remote build context required explicitly passing
the frontend ref to the kokkuri CLI or defining BUILD_FRONTEND
. This
is undesirable since it means users have to keep their .gitlab-ci.yml
and blubber.yaml
in sync with respect to the frontend and version
that's to be used.
Instead, try to resolve the frontend version from remote contexts by
using the GitLab API to get the contents of the config file.
Additionally, provide an extendable job for setting up remote build
contexts and reconfigure this project's .gitlab-ci.yml
to use it.