move Win32 SearchPath and SHGetFolderPath into the Win32 package

move Win32 SearchPath and SHGetFolderPath into the Win32 package

That completes the transition to Unicode FilePath support in the
directory package on Win32 (#3300).

The main cleanup remaining to do here is to use native Win32
implementations of getPermissions/setPermissions/copyPermissions
instead of calls to stat().

We are very close to being able to remove the last bits of C and
autoconf here...