Fix component wrapper rel option

- code previously assumed that only one rel option would be passed, but you can have more than one in the attribute
- passing more than one previously caused an error even if all of the rels were valid, this change corrects that

lib/govuk_publishing_components/presenters/component_wrapper_helper.rb

@@ -240,7 +240,8 @@ def check_rel_is_valid(rel_attribute)
         return if rel_attribute.blank?
 
         options = %w[alternate author bookmark canonical dns-prefetch external expect help icon license manifest me modulepreload next nofollow noopener noreferrer opener pingback preconnect prefetch preload prerender prev privacy-policy search stylesheet tag terms-of-service]
-        unless options.include? rel_attribute
+        rel_array = rel_attribute.split(" ")
+        unless rel_array.all? { |r| options.include? r }
           raise(ArgumentError, "rel attribute (#{rel_attribute}) is not recognised")
         end
       end

spec/lib/govuk_publishing_components/components/component_wrapper_helper_spec.rb

@@ -397,8 +397,8 @@
       end
 
       it "accepts valid rel value" do
-        component_helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow")
-        expect(component_helper.all_attributes[:rel]).to eql("nofollow")
+        component_helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow noreferrer")
+        expect(component_helper.all_attributes[:rel]).to eql("nofollow noreferrer")
       end
 
       it "can set a rel, overriding a passed value" do