Now that Tor's gitlab has the container registry enabled, we can build a
snowflake container on release, and push the built container to the snowflake
registry.
This is accomplished without using privileged gitlab runners, via kaniko.
This would speed up snowflake updates for people running the docker
container. It would also mean that the 'docker-snowflake-proxy' project would no
longer need to exist.
Fixes docker-snowflake-proxy#10
Fixes docker-snowflake-proxy#13