Prepare LoadAsciiTest to handle more numbers of columns re #4464

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>
Skeleton extension of LoadAsciiTest re #4464

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>
Merge branch 'feature/4464_ascii_xerror' into develop