HPCC-7863 Can't read local files with special chars in filename

This is a partial fix, but should improve most cases (and make none worse).

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5644 from richardkchapman/local-write

HPCC-7863 Can't read local files with special chars in filename

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>