added experience tracking and automatic role assigning at given levels

includes: set role command to set a role to a given level (it clears out previous levels)
automatic level config generation on startup
min/max/multiplier configuration
job to persist the xp of the previous minute
added delayed scheduler start, so that events have a discord context in order to function
added role listener to automatically add and mark roles when they are created/deleted
fixed user in a server not being created correctly
added role service to give users role given by id
added server reference to role

abstracto-application/abstracto-modules/pom.xml

@@ -14,6 +14,7 @@
     <modules>
         <module>moderation</module>
         <module>utility</module>
+        <module>experience-tracking</module>
     </modules>