Fix report card (#1845)

* fix: report card

Fix and simplify calculation of the number of assignments a user solved.
Rename `UserTracker` to `UserProgress`
Rename `LessonTracker` to `LessonProgress`
Rename tables in database

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

@@ -54,7 +54,7 @@ public class Assignment {
 
   @Transient private List<String> hints;
 
-  private Assignment() {
+  protected Assignment() {
     // Hibernate
   }