Add non-functioning ConvertFullprofToXml algorithm re #7617

I've left some code in it from LoadFullprofResolution, which could be useful. If I end up using a lot of the code without much modification, then it should go in a class for use by both algorithms.

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>
Change error message re #7617

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>
Merge branch 'feature/7617_fullprof_to_xml' into develop