Refactor SplashScreenAnimation so it can be reused in other parts of the code.

Bug: 202826469
Test: manual
Change-Id: Ib2ce8b8b69bc3f9e4b3003978bac8b3884563678
diff --git a/libs/WindowManager/Shell/Android.bp b/libs/WindowManager/Shell/Android.bp
index 82573b2..f615ad6 100644
--- a/libs/WindowManager/Shell/Android.bp
+++ b/libs/WindowManager/Shell/Android.bp
@@ -45,6 +45,9 @@
         "src/com/android/wm/shell/util/**/*.java",
         "src/com/android/wm/shell/common/split/SplitScreenConstants.java",
         "src/com/android/wm/shell/sysui/ShellSharedConstants.java",
+        "src/com/android/wm/shell/common/TransactionPool.java",
+        "src/com/android/wm/shell/animation/Interpolators.java",
+        "src/com/android/wm/shell/startingsurface/SplashScreenExitAnimationUtils.java",
     ],
     path: "src",
 }