Recreate the opt-in/opt-out logic for deepcopy

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.

pkg/runtime/doc.go

@@ -42,6 +42,6 @@ limitations under the License.
 // As a bonus, a few common types useful from all api objects and versions
 // are provided in types.go.
 
-// +k8s:deepcopy-gen=generate
+// +k8s:deepcopy-gen=package
 
 package runtime