Use camel cased attribute name availableRelationCandidates` in `_links` instead of underscored version

frontend/src/app/components/wp-relations/wp-relations-create/wp-relations-autocomplete/wp-relations-autocomplete.upgraded.component.ts

@@ -103,7 +103,7 @@ export class WpRelationsAutocompleteComponent implements OnInit {
   private autocompleteWorkPackages(query:string):Promise<WorkPackageResource[]> {
     this.$element.find('.ui-autocomplete--loading').show();
 
-    return this.workPackage.available_relation_candidates.$link.$fetch({
+    return this.workPackage.availableRelationCandidates.$link.$fetch({
       query: query,
       type: this.filterCandidatesFor || this.selectedRelationType
     }).then((collection:CollectionResource) => {

lib/api/v3/work_packages/work_package_representer.rb

@@ -134,7 +134,7 @@ module API
           }
         end
 
-        link :available_relation_candidates do
+        link :availableRelationCandidates do
           next if represented.new_record?
 
           {