ExpandFileNameCase function will return the full path as on disk case
type TFilenameCaseMatch = (
mkNone, No file was found
mkExactMatch, The filename can be used to refer to a file on the system (findfirst will find it).
mkSingleMatch, Exactly one match was found, but case didn't match.
mkAmbiguous More than one file will match the filename in a case-insensitive way