Merge remote branch 'origin/feature/7868_load_history_option'
Merge remote-tracking branch 'origin/feature/7639_Add_support_for_ICAT4_interface'
Merge remote-tracking branch 'origin/feature/7639_Add_support_for_ICAT4_interface'
Start and end date independent of one another. Refs #7871.

- Had to remove check in `CatalogSearch.cpp` as endDate won't appear empty since it's set to the unix epox (1970-01-01 00:00:00) if user doesn't input anything.
- Simplified the query if both start and end date are selected.
Merge branch 'feature/7871_icat_independent_search_controls' into develop