整理了Serein.Library项目类文件，IDynamicContext、DynamicContext接口名称及实现类改为IFlowContext、FlowContext，使其与流程其它接口类命名风格统一。

Library/Api/IFlowNode.cs

@@ -123,6 +123,6 @@ namespace Serein.Library.Api
         /// <param name="context"></param>
         /// <param name="token"></param>
         /// <returns></returns>
-        Task<FlowResult> ExecutingAsync(IDynamicContext context, CancellationToken token);
+        Task<FlowResult> ExecutingAsync(IFlowContext context, CancellationToken token);
     }
 }