add a prominent way to easily find or create an edition from an ISBN

[maxlath]

A pattern that seems to happen now and then: a user has ISBNs but doesn't go through the barcode scanner or the importer, and ends up finding more convenient to search a work by label, then create a new work if missing, and then to try to "add an edition by ISBN"

The current default add layout doesn't give any clue where to go when you have an ISBN

The solution could be as simple as adding a "search by ISBN" in this initial section