Summary: Leverage props.isInProgress to disable the confirmation button.
Details: introduced a generic isInProgress prop which should be used in lieu of props like claimedReturnInProgress or declarationInProgress that pollute this generic component with business logic they don't need to know about.
Acceptance criteria:

• Code which passes declarationInProgress to <ModalContent> is refactored to pass isInProgress instead.

• declarationInProgress prop is removed from <ModalContent>.