feat: Quick Fix - relationMode : missing foreign keys' indexes

[Druue]

Per implementation of #1296 a warning will be displayed given a field being referenced within an @relation that hasn't been referenced inside of an @@index clause. This could be quick-fixable.
Internal Reference Doc

--- Before ---

# relationMode = "prisma"

model OrderHistory {
  id        Int      @id
  order     Order    @relation(fields: [orderId], references: [orderId])
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ # Warning Squiggly
  orderId   String
}

--- After ---

model OrderHistory {
  id        Int      @id
  order     Order    @relation(fields: [orderId], references: [orderId])
  orderId   String
  
  @@index([orderId])
}