refactored some things in experience tracking
changed the paging behaviour for leader board and added check for negative numbers
fixed rank not being correct for further pages
added test-common module to have some common code für tests
fixed command creation
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
