Migrate PiP2 flag to aconfig

Bug: 304838465
Test: m -j
Flag: ACONFIG com.android.wm.shell.enable_pip2_implementation DEVELOPMENT
Change-Id: I84dd3740915869ff913919b926110b4ae14dcb12
diff --git a/libs/WindowManager/Shell/aconfig/multitasking.aconfig b/libs/WindowManager/Shell/aconfig/multitasking.aconfig
index c366ccd..4d2d960 100644
--- a/libs/WindowManager/Shell/aconfig/multitasking.aconfig
+++ b/libs/WindowManager/Shell/aconfig/multitasking.aconfig
@@ -42,3 +42,11 @@
     description: "Enables PiP UI state callback on entering"
     bug: "303718131"
 }
+
+flag {
+    name: "enable_pip2_implementation"
+    namespace: "multitasking"
+    description: "Enables the new implementation of PiP (PiP2)"
+    bug: "290220798"
+    is_fixed_read_only: true
+}