[Material Next] Support "Learn more" for help link

Allow CaptionManager, Magnification, Color correction, Color inversion,
Time to take action, and Autoclick.

Bug: 187671696
Test: make RunSettingsRoboTests -j52 ROBOTEST_FILTER=AccessibilityFooterPreferenceTest
Change-Id: I9d753243d4f61b6b3d58b50425b7a75a812a481d

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

@@ -34,4 +34,9 @@ public class AccessibilityControlTimeoutFooterPreferenceController extends
     protected String getLabelName() {
         return mContext.getString(R.string.accessibility_setting_item_control_timeout_title);
     }
+
+    @Override
+    protected int getHelpResource() {
+        return R.string.help_url_timeout;
+    }
 }