【Feature】添加一个判定版本是否拉取的方法；

UpmGitTool/Assets/Scritps/Utils/Lib.cs

@@ -102,6 +102,17 @@
             return pkg.InstallVersion == version;
         }
 
+        /// <summary>
+        /// 当前版本/包是否是在拉取中；
+        /// </summary>
+        public static bool IsFetching(this UpmPackageVersion version)
+        {
+            if (version == null) return false;
+            var pkg = AppState.FindPackage(version.Name);
+            if (pkg == null) return false;
+            return pkg.IsFetching;
+        }
+
         public static E_PackageState GetState(this UPackage pkg)
         {
             if (pkg == null) return E_PackageState.None;