A simple mod to "properly" modify mobcaps

This mod just modifies SpawnGroup enum getters to get the values from config instead. 100% Without magic.

Works on both client and server, not required on client.

Configures for each spawn group:

• Mob cap
• Despawn start range (the 300s one) (aka 5 min)
• Immediate despawn range
• Is peaceful?
• Is rare? (20s spawn cycle)

Try out Per Player Spawns ported to >=1.16 by me