Derive constructor-name-based prisms generically.

Running example:

>>> :set -XTypeApplications
>>> :set -XDataKinds
>>> :set -XDeriveGeneric
>>> :set -XFlexibleContexts
>>> :set -XTypeFamilies
>>> import GHC.Generics
>>> import Control.Lens
>>> :m +Data.Generics.Product.Fields
>>> :m +Data.Function
>>> :{
data Animal a
  = Dog (Dog a)
  | Cat Name Age
  | Duck Age
  deriving (Generic, Show)
data Dog a
  = MkDog
  { name   :: Name
  , age    :: Age
  , fieldA :: a
  }
  deriving Show
type Name = String
type Age  = Int
dog, cat, duck :: Animal Int
dog = Dog (MkDog "Shep" 3 30)
cat = Cat "Mog" 5
duck = Duck 2
:}