Add amenity=social_facility to a future version of the schema

[SomeoneElseOSM]

Currently at https://taginfo.openstreetmap.org/keys/amenity#values there are 167k of these worldwide, so it's a frequently used value. Usage is spread fairly evenly across the world https://taginfo.openstreetmap.org/tags/amenity=social_facility#map ; It is used more in the northern hemisphere than the south, but there it is widely spread out. It's documented at https://wiki.openstreetmap.org/wiki/Tag%3Aamenity%3Dsocial_facility .

It would add value to a general purpose map style that may want to use the Shortbread schema.

It would make sense to add it to: https://shortbread-tiles.org/schema/1.1/#layer-pois to mirror amenity=place_of_worship et al.

In addition, it would make sense to write any non-null social_facility value through as an extra tag, like denomination is for amenity=place_of_worship.