Add "Attribute as Entity" feature

Some cards now support selection of attributes as well as entities, however there are a lot of places where it’s not available, so I end up creating sensor (usually) templates exposing the attributes as entities.

Suggest a helper similar to “Switch as X” that allows an attribute to be promoted to an entity.

That’s a great idea. Tricky though as there are different types of entity you might want depending on the attribute type (boolean vs numeric, vs string).

Would be better if the integration drops the attributes and create sensors instead as this is the way it’s moving anyway but I get this will not happen overnight.