Don't allow dreaming for users that can't dream.

DreamManagerService#canStartDreaming should not return true if the
current user is not allowed to dream.

Bug: 261907079
Test: manually by switching to a user that can't dream and making
sure that the screen turns off on power press while docked.

Change-Id: Ia4a46dff5360d3565762b82fb4353e66f0b8f661

services/core/java/com/android/server/dreams/DreamManagerService.java

@@ -379,6 +379,10 @@ public final class DreamManagerService extends SystemService {
                 return false;
             }
 
+            if (!dreamsEnabledForUser(ActivityManager.getCurrentUser())) {
+                return false;
+            }
+
             if ((mWhenToDream & DREAM_ON_CHARGE) == DREAM_ON_CHARGE) {
                 return mIsCharging;
             }