This drives conversion generation from file tags like:
// +conversion-gen=k8s.io/my/internal/version
.. rather than hardcoded lists of packages.
The only net change in generated code can be explained as correct. Previously
it didn't know that conversion was available.
This drives most of the logic of deep-copy generation from tags like:
// +deepcopy-gen=package
..rather than hardcoded lists of packages. This will make it possible to
subsequently generate code ONLY for packages that need it *right now*, rather
than all of them always.
Also remove pkgs that really do not need deep-copies (no symbols used
anywhere).
