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-container/src/main/resources/application-webgoat.properties

@@ -29,7 +29,6 @@ logging.level.org.owasp=DEBUG
 logging.level.org.owasp.webgoat=DEBUG
 
 webgoat.start.hsqldb=true
-webgoat.clean=false
 webgoat.server.directory=${user.home}/.webgoat-${webgoat.build.version}/
 webgoat.user.directory=${user.home}/.webgoat-${webgoat.build.version}/
 webgoat.build.version=@project.version@