Add a flag to fix rotation to user rotation only.

It also does a few more things:
1. Add a command to manually test the flag.
2. Refactor DisplayRotation a bit to make it unit testable.
3. Add some core unit tests for DisplayRotation.

Bug: 113252523
Test: Manual test.
atest WmTests:DisplayRotationTests

Change-Id: I00c4a44e4d2f637590e8b13f7e6194624c04c58f
diff --git a/services/core/java/com/android/server/wm/ScreenRotationAnimation.java b/services/core/java/com/android/server/wm/ScreenRotationAnimation.java
index df97027..e0c913b 100644
--- a/services/core/java/com/android/server/wm/ScreenRotationAnimation.java
+++ b/services/core/java/com/android/server/wm/ScreenRotationAnimation.java
@@ -222,7 +222,7 @@
     }
 
     public ScreenRotationAnimation(Context context, DisplayContent displayContent,
-            boolean forceDefaultOrientation, boolean isSecure, WindowManagerService service) {
+            boolean fixedToUserRotation, boolean isSecure, WindowManagerService service) {
         mService = service;
         mContext = context;
         mDisplayContent = displayContent;
@@ -234,7 +234,7 @@
         final int originalWidth;
         final int originalHeight;
         DisplayInfo displayInfo = displayContent.getDisplayInfo();
-        if (forceDefaultOrientation) {
+        if (fixedToUserRotation) {
             // Emulated orientation.
             mForceDefaultOrientation = true;
             originalWidth = displayContent.mBaseDisplayWidth;