Date/Time field placeholders should be represent output format

When using date and time fields, the field placeholder uses the format tokens rather than the output format, which are unexpected formats for editors.

For example: a time field with “h:mm a” could display “1:00 am” or some other representative time to show the editor how the time should be entered. The date field is has the same issue: “MMMM D, YYYY” would be better represented as “January 1, 2026” to illustrate the resulting format. The placeholder could always take the minimum or maximum of the token as a general rule.