Adding feature flag and replace existing boolean with settings check

Test: Locally tested + AccessibilityUserStateTest
Bug: 282039824

Change-Id: I1706629c7505e396d8a13981488bc7b52186ef2a
diff --git a/services/accessibility/accessibility.aconfig b/services/accessibility/accessibility.aconfig
index a754ba5..997f3af 100644
--- a/services/accessibility/accessibility.aconfig
+++ b/services/accessibility/accessibility.aconfig
@@ -59,6 +59,13 @@
 }
 
 flag {
+    name: "enable_magnification_one_finger_panning_gesture"
+    namespace: "accessibility"
+    description: "Whether to allow easy-mode (one finger panning gesture) for magnification"
+    bug: "282039824"
+}
+
+flag {
     name: "fix_drag_pointer_when_ending_drag"
     namespace: "accessibility"
     description: "Send the correct pointer id when transitioning from dragging to delegating states."