feat: Introduce Playwright for UI testing

Instead of using Robot Framework which does not run during a `mvn install`. Playwright seems to be the better approach. We can now write them as normal JUnit test and they are executed during a build.

Additionally this PR solves some interesting bugs found during writing Playwright tests:

- A reset of a lesson removes all assignments as a result another user wouldn't see any assignments
- If someone solves an assignment the assignment automatically got solved for a new user since the assignment included the `solved` flag which immediately got copied to new lesson progress.
- Introduction of assignment progress linking a assignment not directly to all users.

src/main/java/org/owasp/webgoat/container/lessons/Assignment.java

@@ -51,7 +51,6 @@ public class Assignment {
 
   private String name;
   private String path;
-  private boolean solved = false;
 
   @Transient private List<String> hints;
 
@@ -75,8 +74,4 @@ public class Assignment {
     this.path = path;
     this.hints = hints;
   }
-
-  public void solved() {
-    this.solved = true;
-  }
 }

src/main/java/org/owasp/webgoat/container/lessons/LessonName.java

@@ -18,4 +18,9 @@ public record LessonName(String lessonName) {
       lessonName = lessonName.substring(0, lessonName.indexOf(".lesson"));
     }
   }
+
+  @Override
+  public String toString() {
+    return lessonName;
+  }
 }