Add a new feature flag for new pip size spec logic

Added a new feature flag got the new pipi size spec logic
that optimizes pip sizing for large screens in particular

Bug: 198643358

Test: mp droid

Change-Id: I20c6f39c07e75b52bc1016444287b8ae4bd844bb

packages/SystemUI/src/com/android/systemui/flags/Flags.kt

@@ -438,6 +438,12 @@ object Flags {
             teamfood = false
         )
 
+    // TODO(b/198643358): Tracking bug
+    @Keep
+    @JvmField
+    val ENABLE_PIP_SIZE_LARGE_SCREEN =
+        sysPropBooleanFlag(1114, "persist.wm.debug.enable_pip_size_large_screen", default = false)
+
     // 1200 - predictive back
     @Keep
     @JvmField