完成mvvm模式下，画布、节点编辑的基本重构

Workbench/Api/IFlowCanvas.cs

@@ -0,0 +1,68 @@
+using Serein.Library;
+using Serein.Workbench.Node.View;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Serein.Workbench.Api
+{
+    /// <summary>
+    /// 流程画布
+    /// </summary>
+    public interface IFlowCanvas
+    {
+        /// <summary>
+        /// 画布标识
+        /// </summary>
+        string Guid { get; }
+
+        /// <summary>
+        /// 画布名称
+        /// </summary>
+        string Name { get; }
+
+        /// <summary>
+        /// 移除节点
+        /// </summary>
+        void Remove(NodeControlBase nodeControl);
+
+        /// <summary>
+        /// 添加节点
+        /// </summary>
+        void Add(NodeControlBase nodeControl);
+
+        /// <summary>
+        /// 创建节点之间方法调用关系
+        /// </summary>
+        /// <param name="fromNodeControl">调用顺序中的起始节点</param>
+        /// <param name="toNodeControl">下一节点</param>
+        /// <param name="type">调用类型</param>
+        void CreateInvokeConnection(NodeControlBase fromNodeControl, NodeControlBase toNodeControl, ConnectionInvokeType type);
+
+        /// <summary>
+        /// 移除节点之间的调用关系
+        /// </summary>
+        /// <param name="fromNodeControl">调用顺序中的起始节点</param>
+        /// <param name="toNodeControl">下一节点</param>
+        void RemoveInvokeConnection(NodeControlBase fromNodeControl, NodeControlBase toNodeControl);
+
+        /// <summary>
+        /// 创建节点之间的参数传递关系
+        /// </summary>
+        /// <param name="fromNodeControl">参数来源节点</param>
+        /// <param name="toNodeControl">获取参数的节点</param>
+        /// <param name="type">指示参数是如何获取的</param>
+        /// <param name="index">作用在节点的第几个入参</param>
+        void CreateArgConnection(NodeControlBase fromNodeControl, NodeControlBase toNodeControl, ConnectionArgSourceType type, int index);
+
+        /// <summary>
+        /// 移除节点之间的参数传递关系
+        /// </summary>
+        /// <param name="fromNodeControl">参数来源节点</param>
+        /// <param name="toNodeControl">获取参数的节点</param>
+        /// <param name="index">移除节点第几个入参</param>
+        void RemoveArgConnection(NodeControlBase fromNodeControl, NodeControlBase toNodeControl, int index);
+    }
+}