Generate helpers for immutable collections/dictionaries

[carldebilly]

Feature request

Should generate helpers to manage collections and dictionaries on immutable entities.

Example

Declaration

  [GeneratedImmutable]
  public class MyClass
  {
    public ImmutableArray<string> Favorites { get; }
    public ImmutableDictionary<string, string> Settings { get; }
  }

Usage

  public void Do()
  {
    var a = new MyClass();
    var b = a.WithAddFavorite("ID01");
    var c = b.WithSetting("owner", "uno platform");
  }

Features

• Should support implementations of IImmutableList<T>, IImmutableSet<T>, IImmutableQueue<T>, IImmutableStack<T>, IImmutableDictionary<TKey, TValue>.
• Should handle null