Move to configurate for paper.yml (#7609)

patches/server/Add-paper-mobcaps-and-paper-playermobcaps.patch

@@ -208,7 +208,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        final ServerPlayer serverPlayer = ((CraftPlayer) player).getHandle();
 +        final ServerLevel level = serverPlayer.getLevel();
 +
-+        if (!level.paperConfig.perPlayerMobSpawns) {
++        if (!level.paperConfig().entities.spawning.perPlayerMobSpawns) {
 +            sender.sendMessage(Component.text("Use '/paper mobcaps' for worlds where per-player mob spawning is disabled.", NamedTextColor.RED));
 +            return;
 +        }