Make fields mandatory on non-po invoices based on distribution combination logic

Summary: We're trying to make our project fields mandatory for non-po invoices, but only if our distribution combination has a specific segment. We've asked about this a little bit with Oracle, and they've comeback that this is possible, but it would have to be the entire dist. combo string. So, we're thinking we might need code add to the fields in the invoice UI (added through edit pages) that compares the distro field to a mapping set of the full strings that are possible. We've worked with each of these pieces, but not really sure how to get them to