ENH: checking of foreign keys and missing columns.

src/caosadvancedtools/table_json_conversion/convert.py

...le_json_conversion/data/multiple_choice_data_missing.xlsx

...son_conversion/data/multiple_refs_data_wrong_foreign.xlsx

...tests/table_json_conversion/data/simple_data_missing.xlsx

...table_json_conversion/data/simple_data_wrong_foreign.xlsx

unittests/table_json_conversion/test_read_data.py