feat: we can now create junctions on Windows

[quintesse]

Fixes #1793

[quintesse]

Updated PR with simplified code using cmd /c mklink /j .... to create junctions.

The createLink() will now also automatically distinguish between links to files and directories and use junctions for directories on Windows, while still using sym links for files (and possibly failing and explaining the user what to do to fix it).

[jcrben]

@quintesse @maxandersen thoughts on merging this?

[maxandersen]

@quintesse didnt we have some concern with this ?

I can definitely give it a go again but feel like there was still a higher permission level needed still or was that fixed?

[quintesse]

@maxandersen no, on Windows it will use an external command (that should exist on all modern Windows versions) that needs no extra privileges to create a junction when dealing with links to folders. Only when we use links to files (as for the edit command) will we fall back to creating symbolic links which still need the same privileges as before. So worst case it does the same as what JBang does right now.