Refactor help menu stuff into a controller

This is a clean up to action bar menu item pattern, we will use the same
pattern to build search icon on all pages in a later change.

Bug: 68814716
Test: robotests
Change-Id: Iedd3ec263e8ccb63ed75ec7a95b28c00878b1de4

src/com/android/settings/accessibility/AccessibilityShortcutPreferenceFragment.java

@@ -51,7 +51,7 @@ public class AccessibilityShortcutPreferenceFragment extends ToggleFeaturePrefer
     }
 
     @Override
-    protected int getHelpResource() {
+    public int getHelpResource() {
         return R.string.help_url_accessibility_shortcut;
     }