Use file tags to generate deep-copies

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).

pkg/apis/authorization/v1beta1/doc.go

@@ -14,5 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// +k8s:deepcopy-gen=register
+
 // +genconversion=true
 package v1beta1