LazUtils: move more Utf8 file routines to LazFileUtils (and inline them in FileUtil):
DirPathExists, CompareFilenames, CompareFilenamesIgnoreCase.


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41354 4005530d-fff6-0310-9dd1-cebe43e6787f