Windows: Support long filenames in more (possibly all) of the code

Works around this bug in unix-compat:
https://github.com/jacobstanley/unix-compat/issues/56
getFileStatus and other FilePath using functions in unix-compat do not do
UNC conversion on Windows.

Made Utility.RawFilePath use convertToWindowsNativeNamespace to do the
necessary conversion on windows to support long filenames.

Audited all imports of System.PosixCompat.Files to make sure that no
functions that operate on FilePath were imported from it. Instead, use
the equvilants from Utility.RawFilePath. In particular the
re-export of that module in Common had to be removed, which led to lots
of other changes throughout the code.

The changes to Build.Configure, Build.DesktopFile, and Build.TestConfig
make Utility.Directory not be needed to build setup. And so let it use
Utility.RawFilePath, which depends on unix, which cannot be in
setup-depends.

Sponsored-by: Dartmouth College's Datalad project

Annex/CopyFile.hs

@@ -15,10 +15,12 @@ import Utility.CopyFile
 import Utility.FileMode
 import Utility.Touch
 import Utility.Hash (IncrementalVerifier(..))
+import qualified Utility.RawFilePath as R
 
 import Control.Concurrent
 import qualified Data.ByteString as S
 import Data.Time.Clock.POSIX
+import System.PosixCompat.Files (fileMode)
 
 -- To avoid the overhead of trying copy-on-write every time, it's tried
 -- once and if it fails, is not tried again.
@@ -101,9 +103,9 @@ fileCopier copycowtried src dest meterupdate iv =
 			fileContentCopier hsrc dest meterupdate iv
 		
 		-- Copy src mode and mtime.
-		mode <- fileMode <$> getFileStatus src
+		mode <- fileMode <$> R.getFileStatus (toRawFilePath src)
 		mtime <- utcTimeToPOSIXSeconds <$> getModificationTime src
-		setFileMode dest mode
+		R.setFileMode dest' mode
 		touch dest' mtime False
 
 		return Copied