Add 'nativecontract' command (#607)

* 打开钱包当文件不存在时错误提示更友好

* Show wallet height when executing "show state" command. Keep in line with neo-gui.

* fixed bug

* 修复Bug

* optimize

* fix

* Add 'nativecontract' command

* update

* update

Co-authored-by: Erik Zhang <erik@vcage.com>
Co-authored-by: Owen Zhang <38493437+superboyiii@users.noreply.github.com>

neo-cli/CLI/MainService.Native.cs

@@ -0,0 +1,19 @@
+using Neo.ConsoleService;
+using Neo.SmartContract.Native;
+using System;
+using System.Linq;
+
+namespace Neo.CLI
+{
+    partial class MainService
+    {
+        /// <summary>
+        /// Process "list nativecontract" command
+        /// </summary>
+        [ConsoleCommand("list nativecontract", Category = "Native Contract")]
+        private void OnListNativeContract()
+        {
+            NativeContract.Contracts.ToList().ForEach(p => Console.WriteLine("\t" + p.Name + "\t" + p.Hash));
+        }
+    }
+}