HPCC-11897 Spaces in filenames should be allowed

While it might have been better not to allow them from the start (arguable),
it does not seem like a good idea to make it impossible to read files in 5.0
that were legally created with earlier versions...

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
I guess if they have 4.x and 5.x on the same dali then they may not lock the same thing.  It would need to be an unusual filename, so probably not an issue in the real world.