[#76021] Allow only USA-format (MM/DD/YYYY) dates in order imports

It accepts 1 or 2 digit months and dates, 4 digit years, and they must be in USA order (month/day/year).
Do you think it would be worth using the `I18n.l` helpers and putting this format into the locale file? Then we can slowly switching over as we touch other pieces of the code that are using this same format?