Support for yarn projects not in the folder root

[actioninja]

Currently this extension only supports providing tasks for yarn projects in the root of the opened folder

On https://github.com/tgstation/tgstation we're using a yarn project that's in a subfolder compared to the main root so this plugin fails to detect and provide tasks for it.

This is more of a feature request than a bug, but it would be nice if situations like this were supported.

[dillonKneeland]

@actioninja Thanks for the issue and sorry for taking a bit to respond. I'll look into this when I get home. You can also always feel free to create a pull request if you've figured it out on your own.