Could not auto close unsaved editor when delete

The newly added "delete" feature #343 works well when we try to delete unchanged files. However, if we try to delete file with unsaved changes, the editor will not be closed and will looks like below:

This is not consistent with native file explorer's behavior and may also cause user lose their changes before deletion. However, this part is hard to fix due to API limitation, since many needed functions are encapsulated within the implementation of VS Code built-in commands. If microsoft/vscode#107566 could be solved, we can fix this problem easily.

从 issue #343 的删除功能开始，在 VS Code 扩展中复现删除包含未保存更改的文件。阅读 microsoft/vscode#107566 以了解 API 限制；完成的标准是编辑器在不危及未保存更改的情况下，以与原生文件资源管理器行为一致的方式关闭。