Magisterium

Update the mod to 1.21.2

• ModFest-specific features were removed (the enableMagisteriumPlaygrounds game rule, /magisterium playgrounds ... commands, and magisterium:data_driven_page item)
• due to the recipe changes in 1.21.2, spells use custom data loader (once again) instead of being recipes, but they are still server-sided and sent to client on joining the server
  • now the synced data lives in data/<namespace>/magisterium/pages/ and the server-only in data/<namespace>/magisterium/effects/
  • many spell effect properties are now read from their json files

Wasn't tested on Connector/NeoForge as it's not available yet