ShortcutPreference Toggle design.

- For target SDK < 30 app show as preference item to trigger shortcut on/off.
- For target SDK >= 30 app show two item: the left one can edit shortcut and the right one be a on/off trigger button.

The design is reference from WIFI setting which has similar comportment.

Bug: 148989269
Test: Test result in Buganizer.

Change-Id: I815206d9e885c01bf3e6445820176aed4a743323

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

@@ -43,7 +43,7 @@ public class LegacyAccessibilityServicePreferenceFragment extends
         final CharSequence hardwareTitle = getPrefContext().getText(
                 R.string.accessibility_shortcut_edit_dialog_title_hardware);
         mShortcutPreference.setSummary(hardwareTitle);
-        mShortcutPreference.setSettingsVisibility(View.GONE);
+        mShortcutPreference.setSettingsEditable(false);
 
         setAllowedPreferredShortcutType(UserShortcutType.HARDWARE);
     }