The changes to make suffix more general mean that it can't be tested from
POLARIS unit tests any more, so a suffix has been added to the POLARIS
unit test as well

The loader now expects VirtualChopper.chopper1_average_phase and
VirtualChopper.chopper2_average_speed to contain the correct values and
will not work with old D17 NeXus files where these values were swapped.
The files used in unit testing were corrected, as well.

Re #20978

Merge to ensure CrystalFieldFunction is available and up to date.

Refs #21000

Refs #21000

In case of LoadGAUSSIAN and LoadCRYSTAL look for isotopes in the approximated way. Update unit test.

Add check_isotopes_substitution to GeneralAbInitioProgram. Add reading masses from file to LoadCASTEP, LoadCRYSTAL, LoadGAUSSIAN, LoadDMOL3.