We were very inconsistent regarding these rules.
Personally I prefer no empty lines around blocks, clases, etc... as
recommended by the Ruby style guide [1], and they're the default values
in rubocop, so those are the settings I'm applying.
The exception is the `private` access modifier, since we were leaving
empty lines around it most of the time. That's the default rubocop rule
as well. Personally I don't have a strong preference about this one.
[1] https://rubystyle.guide/#empty-lines-around-bodies
By doing so and including it in ActionDispatch::Routing::UrlFor, we make
it available in controllers, helpers and specs, and so we can remove the
duplication we had there with methods dealing with the same problem.
Even if monkey-patching is ugly, using a different module and executing
ActionDispatch::Routing::UrlFor.send(:include, MyModule) wouldn't make
the method available in the controller.
Notifications usually link to the associated notifiable, but the new
AdminNotifications have a link attribute that may be empty or contain an
external or internal url.
