True if Directory contains a directory or regular file
(respectively) named BaseName and the file's absolute path is
FullName. If Directory is not given, it defaults to the current
working directory. If Pattern is given, only succeeds if
BaseName also matches that glob pattern.
These predicates enumerate all matching files on backtracking.
This is also the intended usage pattern. For checking if a
specific file/directory exists, or to get its absolute path,
it's better to use file_exists/1, directory_exists/1, or
absolute_file_name/3.
