This minimizes the number of functions generated. It also breaks the chain of
symbol dependencies to pkg/conversion, so we can remove now-unreferenced
(previously unused but referenced) conversion deep-copies.
This is the last piece of Clayton's #26179 to be implemented with file tags.
All diffs are accounted for. Followup will use this to streamline some
packages.
Also add some V(5) debugging - it was helpful in diagnosing various issues, it
may be helpful again.
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).
