[A11y] Add aconfig flag for magnifier keyboard control

Bug: b/355487062
Flag: com.android.server.accessibility.enable_magnification_keyboard_control
Test: None, aconfig flag only
Change-Id: Ic8911d2ff6cfe1d6b4e8eb13b53f4ab9caf8307a
diff --git a/services/accessibility/accessibility.aconfig b/services/accessibility/accessibility.aconfig
index 8e2e0ad..08cc9c3 100644
--- a/services/accessibility/accessibility.aconfig
+++ b/services/accessibility/accessibility.aconfig
@@ -121,6 +121,13 @@
 }
 
 flag {
+    name: "enable_magnification_keyboard_control"
+    namespace: "accessibility"
+    description: "Whether to enable keyboard control for magnification"
+    bug: "355487062"
+}
+
+flag {
     name: "fix_drag_pointer_when_ending_drag"
     namespace: "accessibility"
     description: "Send the correct pointer id when transitioning from dragging to delegating states."