Add per-display RemoteAnimation overrides and flag to disable snapshots

This CL adds a display-level fallback for remoteanimation overrides
and a property to RemoteAnimationAdapter specifying whether it needs
a snapshot for change transitions or not.

During a mode-change, this check for an override and then asks it
whether it needs a snapshot before creating one.

Bug: 113252739
Test: Added AppChangeTransitionTests
Change-Id: I47c933bd08fe512dc6cf029607819e2c908ab4cd
diff --git a/services/tests/wmtests/src/com/android/server/wm/WindowTestUtils.java b/services/tests/wmtests/src/com/android/server/wm/WindowTestUtils.java
index 44e998b..2263cf3 100644
--- a/services/tests/wmtests/src/com/android/server/wm/WindowTestUtils.java
+++ b/services/tests/wmtests/src/com/android/server/wm/WindowTestUtils.java
@@ -152,6 +152,7 @@
     public static class TestAppWindowToken extends AppWindowToken {
         boolean mOnTop = false;
         private Transaction mPendingTransactionOverride;
+        boolean mSkipOnParentSet = true;
 
         private TestAppWindowToken(DisplayContent dc) {
             super(dc.mWmService, new IApplicationToken.Stub() {
@@ -200,7 +201,9 @@
 
         @Override
         void onParentSet() {
-            // Do nothing.
+            if (!mSkipOnParentSet) {
+                super.onParentSet();
+            }
         }
 
         @Override