Make SHORT_EDGES mode only extends on the short edges

- In R, we allow long edge cutouts and therefore a new ALWAYS flag is
added which allow apps to be laid out in all edges. So now we have to
ensure apps with SHORT_EDGES mode to be laid out only in short edges.

- Set wallpapaer window to ALWAYS mode

Bug: 146876976
Test: atest DisplayPolicyLayoutTests
Test: atest WallpaperTests
Change-Id: Iaf820b5c8105927e61b30d389a659b9d28db3f94

core/java/android/view/WindowManager.java

@@ -3687,6 +3687,8 @@ public interface WindowManager extends ViewManager {
                     return "always";
                 case LAYOUT_IN_DISPLAY_CUTOUT_MODE_NEVER:
                     return "never";
+                case LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES:
+                    return "shortEdges";
                 default:
                     return "unknown(" + mode + ")";
             }