Move Magnification Mode Settings to the main page

We move the mode settings because currently there is
only one item in the settings page. To fully test all logic,
we don't use fragament anymore in the controllerTest, and
test the interaction between the controller and the fragment
in the test of these two fragments.

Bug: 182992338
Test: atest ToggleScreenMagnificationPreferenceFragmentTest
      atest MagnificationModePreferenceControllerTest
      atest MagnificationSettingsFragmentTest
      manually test
Change-Id: Ia6b0ea4f116f3215407637d7aeaddb8d8196d8fb

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

@@ -118,16 +118,16 @@ public class AccessibilityEditDialogUtils {
      * Method to show the magnification edit shortcut dialog in Magnification.
      *
      * @param context A valid context
-     * @param dialogTitle The title of magnify edit shortcut dialog
      * @param positiveBtnListener The positive button listener
      * @return A magnification edit shortcut dialog in Magnification
      */
     public static Dialog createMagnificationSwitchShortcutDialog(Context context,
-            CharSequence dialogTitle, CustomButtonsClickListener positiveBtnListener) {
+            CustomButtonsClickListener positiveBtnListener) {
         final View contentView = createSwitchShortcutDialogContentView(context);
         final AlertDialog alertDialog = new AlertDialog.Builder(context)
                 .setView(contentView)
-                .setTitle(dialogTitle)
+                .setTitle(context.getString(
+                        R.string.accessibility_magnification_switch_shortcut_title))
                 .create();
         setCustomButtonsClickListener(alertDialog, contentView,
                 positiveBtnListener, /* negativeBtnListener= */ null);