Add more missing builtin package declarations

* lisp/emacs-lisp/shorthands.el: Declare library as part of the
'emacs' package.
* lisp/epa-ks.el: Declare library as part of the 'epa'
package.  (Bug#55388)

lisp/emacs-lisp/shorthands.el

@@ -4,6 +4,7 @@
 
 ;; Author: João Távora <joaotavora@gmail.com>
 ;; Keywords: lisp
+;; Package: emacs
 
 ;; This file is part of GNU Emacs.
 

lisp/epa-ks.el

@@ -4,6 +4,7 @@
 
 ;; Author: Philip K. <philipk@posteo.net>
 ;; Keywords: PGP, GnuPG
+;; Package: epa
 
 ;; This file is part of GNU Emacs.