Patch socketpair (#576)

* 将sockets分成inet和unix域
- 添加File端点
- 添加SocketPair trait并将Socket trait中的pair相关方法移动
- 添加对SockAddrUn的处理

* 精简SocketHandleItem

* 重构socketpair相关逻辑
- 将File端点换成Inode端点
- 尝试使用SocketInode进行socketpair(未成功)


* 将SocketPair trait合并到Socket trait中，去除downcast

user/dadk/config/test_socket-0.1.0.dadk

@@ -0,0 +1,22 @@
+{
+  "name": "test_socket",
+  "version": "0.1.0",
+  "description": "测试socket",
+  "task_type": {
+    "BuildFromSource": {
+      "Local": {
+        "path": "apps/test_socket"
+      }
+    }
+  },
+  "depends": [],
+  "build": {
+    "build_command": "make install"
+  },
+  "clean": {
+    "clean_command": "make clean"
+  },
+  "install": {
+    "in_dragonos_path": "/"
+  }
+}