Cut a dependency between kubectl and the rest of the repo

The types referenced in credentialprovider are part of a long term api
and will not change, and kubectl doesn't need to take a dependency on this
package in order to do minimal validation here.

build/visible_to/BUILD

@@ -393,6 +393,7 @@ package_group(
         "//pkg/kubectl",
         "//pkg/kubectl/cmd",
         "//pkg/kubectl/generate",
+        "//pkg/kubectl/generate/versioned",
         "//pkg/kubectl/proxy",
     ],
 )