## instance Semigroup/Monoid (f (g a)) => Semigroup/Monoid (Compose f g a)

## Motivation

I am defining a higher-kinded data structure representing configuration:

```
data Config f = Config
{ _port :: f Int
, _db :: f FilePath
}
instance (forall a . Semigroup (f a)) => Semigroup (Config f) where
Config p1 db1 <> Config p2 db2 = Config (p1 <> p2) (db1 <> db2)
instance (forall a . Monoid (f a)) => Monoid (Config f) where
mempty = Config mempty mempty
```

I want to represent partial configs using the `Maybe (Last a))`

Monoid. To make that fit, I have to use `Data.Functor.Compose.Compose`

:

```
type FullConfig = Config Identity
type PartialConfig = Config (Compose Maybe Last)
```

However, `Compose f g a`

has no `Monoid`

instance that uses the underlying `f (g a)`

. At this point I am sad, and have to either write an orphan, or my own `newtype Last a = Last (Maybe a)`

which is the same as `Data.Maybe.Last`

(which was meant to be deprecated in 8.8, according to `base-4.13.0.0`

haddocks?).

## Proposal

Add the following instances (possibly GeneralizedNewtypeDeriving will give them to us):

```
instance Semigroup (f (g a)) => Semigroup (Compose f g a)
instance Monoid (f (g a)) => Monoid (Compose f g a)
```

## Related Issues

#15028 - Deprecate and remove Data.Semigroup.Option; Data.Monoid.{First,Last}

#16636 - Eq1/Show1 etc for Data.Monoid.{First,Last}