Simplify Makefile

A help target has been added that describes each target and groups them
by category.

Remove targets to push/pull images from gcr - now that we only have two
images in this repo manually running the podman commands will be fine

Remove option to push to docker daemon or build with sudo - with buildah
and podman we don't typically need these options

Update build targets - we had some logic in our image and binary
build targets that was overly complicated now that we only have two
images in this repo. Each binary and image has a single target used to
build that particular resource. The names of these targets have been
updated to improve readability.

Random cleanup
- Add phony targets
- Remove relics of the past
- remove images var that is now unused

Author: jmckulk