Fix imports and use request validation functions in search views
Fix imports and use request validation functions in search views

Sends only supported filters/lots that could be set through the user
interface to the search API.

AusDTO/dto-digitalmarketplace-buyer-frontend,mtekel/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend,mtekel/digitalmarketplace-buyer-frontend,AusDTO/dto-digitalmarketplace-buyer-frontend,mtekel/digitalmarketplace-buyer-frontend,mtekel/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend,AusDTO/dto-digitalmarketplace-buyer-frontend,AusDTO/dto-digitalmarketplace-buyer-frontend