Backport #258 to 1.20.1

This fix is pretty critical, affecting world generation and entity
spawning in several mods.

patches/minecraft/net/minecraft/tags/TagLoader.java.patch

@@ -13,7 +13,7 @@
 
     private Either<Collection<TagLoader.EntryWithSource>, Collection<T>> m_215978_(TagEntry.Lookup<T> p_215979_, List<TagLoader.EntryWithSource> p_215980_) {
 -      ImmutableSet.Builder<T> builder = ImmutableSet.builder();
-+      var builder = new java.util.HashSet<T>();
++      var builder = new java.util.LinkedHashSet<T>(); // Set must retain insertion order, some tag consumers rely on this being the case (see NeoForge#256)
        List<TagLoader.EntryWithSource> list = new ArrayList<>();
 
        for(TagLoader.EntryWithSource tagloader$entrywithsource : p_215980_) {