Add IdentifierRef.Pair<TRelation> method

src/gaemstone.ECS/IdentifierRef.cs

@@ -21,10 +21,17 @@ public unsafe class IdentifierRef
 
 	public static IdentifierRef Combine(IdentifierFlags flags, IdentifierRef id)
 		=> new(id.World, Identifier.Combine(flags, id));
+
+	public static IdentifierRef Pair(World world, Entity relation, Entity target)
+		=> new(world, Identifier.Pair(relation, target));
+	public static IdentifierRef Pair(EntityRef relation, EntityRef target)
+		=> Pair(relation.World, relation, target);
 	public static IdentifierRef Pair(EntityRef relation, Entity target)
-		=> new(relation.World, Identifier.Pair(relation, target));
+		=> Pair(relation.World, relation, target);
 	public static IdentifierRef Pair(Entity relation, EntityRef target)
-		=> new(target.World, Identifier.Pair(relation, target));
+		=> Pair(target.World, relation, target);
+	public static IdentifierRef Pair<TRelation>(EntityRef target)
+		=> Pair(target.World.LookupByTypeOrThrow<TRelation>(), target);
 
 	public EntityRef? AsEntity()
 		=> (Flags == default) ? World.LookupAlive(new Entity(new() { Data = Id })) : null;