Switch WindowContainer to use ConfigurationContainer

To reduce implementation dupication.
This also involved moving ConfigurationContainer to the wm package.

Test: bit FrameworksServicesTests:com.android.server.wm.ConfigurationContainerTests
Test: bit FrameworksServicesTests:com.android.server.wm.WindowContainerTests
Test: go/wm-smoke
Change-Id: Ibeca7e2ad2685f0984fccc66852d53ed9af0925f
diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index a37b2e5..dff963a 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -1446,7 +1446,7 @@
     }
 
     @VisibleForTesting
-    int getStaskPosById(int stackId) {
+    int getStackPosById(int stackId) {
         for (int i = mTaskStackContainers.size() - 1; i >= 0; --i) {
             final TaskStack stack = mTaskStackContainers.get(i);
             if (stack.mStackId == stackId) {
@@ -1457,7 +1457,7 @@
     }
 
     @Override
-    void onConfigurationChanged(Configuration newParentConfig) {
+    public void onConfigurationChanged(Configuration newParentConfig) {
         super.onConfigurationChanged(newParentConfig);
 
         // The display size information is heavily dependent on the resources in the current