Only count Natural Spawned mobs towards natural spawn mob limit

This resolves the super common complaint about mobs not spawning.

This was ultimately a flaw in the vanilla count algorithim that allows
spawners and other misc mobs to count against the mob limit, which are
not bounded, and can prevent the entire world from spawning new.

I believe Bukkits changes around persistence may of actually made it
worse than vanilla.

This should fully solve all of the issues around it so that only natural
influences natural spawns.

paper-server/patches/sources/net/minecraft/world/level/NaturalSpawner.java.patch

@@ -14,7 +14,21 @@
  
  public final class NaturalSpawner {
  
-@@ -107,15 +112,31 @@
+@@ -82,6 +87,13 @@
+             MobCategory enumcreaturetype = entity.getType().getCategory();
+ 
+             if (enumcreaturetype != MobCategory.MISC) {
++                // Paper start - Only count natural spawns
++                if (!entity.level().paperConfig().entities.spawning.countAllMobsForSpawning &&
++                    !(entity.spawnReason == org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.NATURAL ||
++                        entity.spawnReason == org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.CHUNK_GEN)) {
++                    continue;
++                }
++                // Paper end - Only count natural spawns
+                 BlockPos blockposition = entity.blockPosition();
+ 
+                 chunkSource.query(ChunkPos.asLong(blockposition), (chunk) -> {
+@@ -107,15 +119,31 @@
          return (Biome) chunk.getNoiseBiome(QuartPos.fromBlock(pos.getX()), QuartPos.fromBlock(pos.getY()), QuartPos.fromBlock(pos.getZ())).value();
      }
  
@@ -48,7 +62,7 @@
                  list.add(enumcreaturetype);
              }
          }
-@@ -164,9 +185,9 @@
+@@ -164,9 +192,9 @@
          StructureManager structuremanager = world.structureManager();
          ChunkGenerator chunkgenerator = world.getChunkSource().getGenerator();
          int i = pos.getY();
@@ -60,7 +74,7 @@
              BlockPos.MutableBlockPos blockposition_mutableblockposition = new BlockPos.MutableBlockPos();
              int j = 0;
              int k = 0;
-@@ -195,7 +216,7 @@
+@@ -195,7 +223,7 @@
                              if (entityhuman != null) {
                                  double d2 = entityhuman.distanceToSqr(d0, (double) i, d1);
  
@@ -69,7 +83,7 @@
                                      if (biomesettingsmobs_c == null) {
                                          Optional<MobSpawnSettings.SpawnerData> optional = NaturalSpawner.getRandomSpawnMobAt(world, structuremanager, chunkgenerator, group, world.random, blockposition_mutableblockposition);
  
-@@ -207,7 +228,13 @@
+@@ -207,7 +235,13 @@
                                          j1 = biomesettingsmobs_c.minCount + world.random.nextInt(1 + biomesettingsmobs_c.maxCount - biomesettingsmobs_c.minCount);
                                      }
  
@@ -84,7 +98,7 @@
                                          Mob entityinsentient = NaturalSpawner.getMobForSpawn(world, biomesettingsmobs_c.type);
  
                                          if (entityinsentient == null) {
-@@ -217,10 +244,15 @@
+@@ -217,10 +251,15 @@
                                          entityinsentient.moveTo(d0, (double) i, d1, world.random.nextFloat() * 360.0F, 0.0F);
                                          if (NaturalSpawner.isValidPositionForMob(world, entityinsentient, d2)) {
                                              groupdataentity = entityinsentient.finalizeSpawn(world, world.getCurrentDifficultyAt(entityinsentient.blockPosition()), EntitySpawnReason.NATURAL, groupdataentity);
@@ -104,7 +118,7 @@
                                              if (j >= entityinsentient.getMaxSpawnClusterSize()) {
                                                  return;
                                              }
-@@ -250,10 +282,31 @@
+@@ -250,10 +289,31 @@
          return squaredDistance <= 576.0D ? false : (world.getSharedSpawnPos().closerToCenterThan(new Vec3((double) pos.getX() + 0.5D, (double) pos.getY(), (double) pos.getZ() + 0.5D), 24.0D) ? false : Objects.equals(new ChunkPos(pos), chunk.getPos()) || world.isNaturalSpawningAllowed((BlockPos) pos));
      }
  
@@ -138,7 +152,7 @@
      }
  
      @Nullable
-@@ -268,6 +321,7 @@
+@@ -268,6 +328,7 @@
              NaturalSpawner.LOGGER.warn("Can't spawn entity of type: {}", BuiltInRegistries.ENTITY_TYPE.getKey(type));
          } catch (Exception exception) {
              NaturalSpawner.LOGGER.warn("Failed to create mob", exception);
@@ -146,7 +160,7 @@
          }
  
          return null;
-@@ -356,6 +410,7 @@
+@@ -356,6 +417,7 @@
                                      entity = biomesettingsmobs_c.type.create(world.getLevel(), EntitySpawnReason.NATURAL);
                                  } catch (Exception exception) {
                                      NaturalSpawner.LOGGER.warn("Failed to create mob", exception);
@@ -154,7 +168,7 @@
                                      continue;
                                  }
  
-@@ -369,7 +424,7 @@
+@@ -369,7 +431,7 @@
  
                                      if (entityinsentient.checkSpawnRules(world, EntitySpawnReason.CHUNK_GENERATION) && entityinsentient.checkSpawnObstruction(world)) {
                                          groupdataentity = entityinsentient.finalizeSpawn(world, world.getCurrentDifficultyAt(entityinsentient.blockPosition()), EntitySpawnReason.CHUNK_GENERATION, groupdataentity);
@@ -163,7 +177,7 @@
                                          flag = true;
                                      }
                                  }
-@@ -482,10 +537,12 @@
+@@ -482,10 +544,12 @@
              return this.unmodifiableMobCategoryCounts;
          }