CRDB: Handle unicode escaping in enum and string defaults in migrate/introspection

[tomhoule]

This schema is not idempotent, but it should be:

         datasource db {
             provider = "postgres"
             url = "postgres://meowmeowmeow"
         }
 
         enum Color {
             Red @map("0")
             Green @map("Grün")
             Blue @map("Blu")
         }
 
         model Test {
             id Int @id
             mainColor Color @default(Green)
             secondaryColor Color @default(Red)
             colorOrdering Color[] @default([Blue, Red, Green, Red, Blue, Red])
         }