Helpful instances for deriving Codec

[bruderj15]

Very often we have types like:

data FooBar a = FooBar
  { _fbId  :: Integer
  , _foo   :: a
  , _bar   :: a
  } deriving stock (Generic)
    deriving anyclass (Codec)

This requires:

instance Codec Integer where
  type Decoded Integer = Integer
  decode _ = Just
  encode = id

Provide such helper instances for standard types.