Splits a Windows path into a drive and path part. The drive can be e.g. C:. It can also be a UNC path (\\server\drive\path).

The equivalent splitDrive for POSIX systems always returns empty drive. Therefore this proc is only necessary on DOS-like file systems (together with Nim's doslikeFileSystem conditional variable).

This proc's use case is to extract path such that it can be manipulated like a POSIX path.

Example:

doAssert splitDrive("C:") == ("C:", "")
doAssert splitDrive(r"C:\") == (r"C:", r"\")
doAssert splitDrive(r"\\server\drive\foo\bar") == (r"\\server\drive", r"\foo\bar")
doAssert splitDrive(r"\\?\UNC\server\share\dir") == (r"\\?\UNC\server\share", r"\dir")