Some functions are not used in HeaderSchema.cs

[wschin]

As title. In class

    [BestFriend]
    internal abstract class FeatureNameCollection : IEnumerable<string>

those functions

        private FeatureNameCollection()
        {
        }

        public static FeatureNameCollection Create(string[] names)
        {
            return Create(Utils.Size(names), names);
        }

        public static FeatureNameCollection Create(RoleMappedSchema schema)
        {
            …
        }

        public static void Save(ModelSaveContext ctx, in VBuffer<ReadOnlyMemory<char>> names)
        {
            …
        }

        public bool TryLookup(string name, out int index)
        {
            …
        }     

are not used.

[Ivanidzo4ka]

• @yaeldekel.
  This class still used in internal repository. I think it's fine to remove this class from this repository, as long as we move that class into internal repo.