Feature/SW-3595 Add info boxes to SAS start page & Eurobonus alert to select-hotel page on SAS
* wip
* feat(SW-3595): Add info boxes to SAS start page
* Add InfoBox to design-system
* Add background gradient to SAS start page
* update variable naming and conditionalize the eurobonus message on select-hotel
* SAS startpage update default message
* make select-hotel a bit more generic with slot={} instead of alert={}
Approved-by: Anton Gunnarsson
