feat(groups/{a,b}*): vim syntax support

Add vim modeline instructing the editor to use syntax plugin provided by apparmor.

Continuation of #391 to keep the diff list relatively short.

apparmor.d/groups/browsers/firefox-glxtest

@@ -26,4 +26,6 @@ profile firefox-glxtest @{exec_path} flags=(attach_disconnected) {
   owner @{PROC}/@{pid}/cmdline r,
 
   include if exists <local/firefox-glxtest>
-}
+}
+
+# vim:syntax=apparmor