Make it optional but only if Workspace is set re #8403

Also add unit test to test failure if neither
OutputTableWorkspace nor Workspace is set.
Also make use of optionality in another unit test.

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>
Clean LoadFullprofResolutionTest.h re #8403
Merge remote-tracking branch 'origin/feature/8403_output_table_ws_optional'