Fix "Invalid base URL" when creating card def inheriting from cross-realm spec#4348

lucaslyl wants to merge 8 commits intomaincardstack/boxel:mainfrom

CS-10590/create-new-card-def-from-listing-hit-invalid-base-urlcardstack/boxel:CS-10590/create-new-card-def-from-listing-hit-invalid-base-urlCopy head branch name to clipboard