Modpack groups

[Skidamek]

• [x] V3 server config & modpack content update
• [x] Server side protocol update
• [ ] Client side new modpack content schema handling
• [ ] Client side ModpackUpdater update
• [ ] Implement functionality for new server config group based modpacks options:
  • [ ] required
  • [ ] checkByDefault
  • [ ] breaksWith
  • [ ] requiredBy
  • [ ] compatibleOS
• [ ] Add additional pack for optional mods free to choose for client
• [ ] Client side GUI
• [ ] Testing

#151 #223