feat(groups/{c,d,f,s}*): vim syntax support

Add vim modeline instructing the editor to use syntax plugin provided by apparmor.
Continuation of #392 to keep the diff list relatively short.

apparmor.d/groups/systemd/systemd-generator-environment-arch

@@ -17,4 +17,6 @@ profile systemd-generator-environment-arch @{exec_path} {
   @{sh_path}        r,
 
   include if exists <local/systemd-generator-environment-arch>
-}
+}
+
+# vim:syntax=apparmor