Add NonEmptyMap and NonEmptySet to containers

[Oleg Grenrus]

Relating to Foldable1/NonEmptyFoldable, based in another discussion (in 
my foldable1 to base proposal), it looks like it might be called 
Semifoldable

See https://mail.haskell.org/pipermail/libraries/2019-October/030030.html

Yet, Semiset is different thing (based on wikipedia: 
https://en.wikipedia.org/wiki/Semiset). NonEmptySet is a good name, it 
doesn't need explanation. If someone feels that it's too long, they can 
introduce `type NESet = NonEmptySet` alias in their development.

- Oleg

On 20.9.2019 4.56, Ruben Astudillo wrote:
> On 19-09-19 22:17, Alexandre Esteves wrote:
>> I do like the sound of `instance Foldable1 Set1` more than I do
>> `instance NonEmptyFoldable NonEmptySet`
>> <https://hackage.haskell.org/package/semigroupoids-5.3.3/docs/Data-Semigroup-Foldable.html#t:Foldable1>
> I prefer it too, I just wish (future) documentation included a little
> explanation on why the suffix 1 was put.
>