Resolve a path to a file. The path may be absolute or my need to be
resolved either relative to the resolver's root directory. The instance
of the resolver determines what the root directory is. The path in the
returned file has been normalized by calling
FilenameNormalization.normalize() or some equivalent.
Parameters:
path - the path to resolve.
Returns:
a File of the resolved, and normalized path. The file
is not guaranteed to exist.