Adjust lesson template (#704)

* Remove method `getId()` from all lessons as it defaults to the class name

* remove clean up endpoint

* remove unused class `RequestParameter`

* remove unused class `PluginLoadingFailure`

* Move `CourseConfiguration` to lesson package

* Add more content around the lesson template lesson and make it visible as a lesson in WebGoat

* Remove explicit invocation `trackProgress()` inside WebGoat framework so assignments only need to return an `AttackResult`

* Put original solution back as well for SQL string injection

* review comments

* Add

webgoat-lessons/insecure-deserialization/src/test/java/org/owasp/webgoat/deserialization/DeserializeTest.java

@@ -28,7 +28,6 @@ public class DeserializeTest extends AssignmentEndpointTest {
         InsecureDeserializationTask insecureTask = new InsecureDeserializationTask();
         init(insecureTask);
         this.mockMvc = standaloneSetup(insecureTask).build();
-        when(webSession.getCurrentLesson()).thenReturn(new InsecureDeserialization());
     }
 
     @Test