Create a Plain formatter

In commerce_price we created two price formatters:
- Default (uses the number format rules to output a formatted price)
- Plain (uses a twig template and lets the themer choose their own output)

In address we also have a default formatter which formats based on the address format. However, we don't have a Plain formatter yet, though it makes a lot of sense to have it.
It would allow people maximum control over the outputted address, and would allow people to format all addresses, regardless of the country, the same way.
There's already a matching D7 feature request with a patch: #1541384: Provide regular theme function for displaying an address as an alternative to formatter plugins.

The default theme function should output the following format:

recipient
organization
address_line1
address_line2
dependent_locality.code
locality.code postal_code administrative_area.code
country.name

The subdivisions and country should have both the code and the name properties available.