Scheduling in webservice

1. QuartzScheduler to delete manifest files on a schedule. Ensures ServerPackCreator always has the latest and greatest Minecraft, Forge and Fabric versions available for validation.
   1. Cleanup modpacks generated from CurseForge.
   2. Cleanup server pack folders (NOT ZIP-archives). This saves diskspace.
   3. Vaildate database entries for available server packs? Would improve safety of entries in downloads-section
   4. Cleanup temp directory where uploaded ZIP-archives are stored