Make URN mandatory for UK schools and NCES ID mandatory for US schools#638

Mohamed-RPF wants to merge 11 commits intomainRaspberryPiFoundation/editor-api:mainfrom

780-improve-urn-nces-id-and-and-school-roll-number-validation-error-message-and-form-state-apiRaspberryPiFoundation/editor-api:780-improve-urn-nces-id-and-and-school-roll-number-validation-error-message-and-form-state-apiCopy head branch name to clipboard