Expanded accessibility search terms

Items with new keywords:
-Accessibility
-Accessibility Menu
-Autoclick
-Live Caption
-Hearing Aids/Devices
-3-button navigation
-Touch & Hold
-Accessibility Timeout

Bug: 278091482
Test: Build SettingsGoogle, change your system language a few times, then check that the search bar responds to the new terms
Change-Id: Iddaf4f378b63f13141c1c52fbb4daa20f90a5ff8

src/com/android/settings/gestures/SystemNavigationGestureSettings.java

@@ -403,6 +403,7 @@ public class SystemNavigationGestureSettings extends RadioButtonPickerFragment i
                         SearchIndexableRaw data = new SearchIndexableRaw(context);
                         data.title = res.getString(R.string.legacy_navigation_title);
                         data.key = KEY_SYSTEM_NAV_3BUTTONS;
+                        data.keywords = res.getString(R.string.keywords_3_button_navigation);
                         result.add(data);
                     }