Refactor the launch connector design for launch and attach debugging

• For the launch debugging, we provide two kinds of implementation: SocketLaunchingConnector and ListeningConnector. Need revisit the design to see whether to keep using one kind of implementation.
• For the attach debugging, support both Socket Attach and Socket Listen. See #415

首先檢視 issue 中描述的 SocketLaunchingConnector 與 ListeningConnector 實作，然後閱讀 #415 以了解 attach 偵錯的背景。當 launch 偵錯確定了 connector 方案，且 attach 偵錯同時支援 Socket Attach 與 Socket Listen 時，設計工作即告完成。