Support tsconfig.json in the subdirectory.

[huww98]

• I have searched through existing issues
• I have read through docs
• I have read FAQ

Info

• Platform: Win
• Vetur version: 0.11.3
• VS Code version: 1.18.1

Problem

Everything works if I put my tsconfig.json in the workspace root directory.

However, this file is not recognized if it is in one of the subdirectory. e.g.: MySolution/MyVueProject/tsconfig.json.

That is to say, if I open MySolution in vs code, not work. However, it works if I open MyVueProject.

This directory structure works well with pure .ts file, the problem only exist with .vue file.

[HerringtonDarkholme]

Dup of #385 and #424