test framework: improved aiXXX commands support:

- added more options for priority control (play single priority, play multiple priorities until stack resolved);
- added more options for step control (play single step, play multiple steps);
- improved compatibility with AI and real time commands (now check commands can be called inside AI controlled steps);
- added tests for assign non-blocked damage;

Mage/src/main/java/mage/constants/PhaseStep.java

@@ -1,5 +1,7 @@
 package mage.constants;
 
+import java.util.Arrays;
+
 /**
  * @author North
  */
@@ -51,6 +53,13 @@ public enum PhaseStep {
         return text;
     }
 
+    public static PhaseStep fromString(String needText) {
+        return Arrays.stream(values())
+                .filter(step -> step.toString().equals(needText))
+                .findFirst()
+                .orElse(null);
+    }
+
     public String getStepText() {
         return stepText;
     }