Fix really_destroy used against a has_one relationship that is soft deleted

[reedstonefood]

I found a bug. The test explains the scenario but I'll explain it here as well.

Given:

class MyModel < ActiveRecord::Base
  acts_as_paranoid
  has_one: linked_model, dependant: destroy
end

class LinkedModel < ActiveRecord::Base
  acts_as_paranoid
end

my_model = MyModel.create!(linked_model: LinkedModel.new)

• ✅ If you run my_model.destroy then both objects get soft-deleted as you would expect
• ❌ However if you then subsequently run my_model.really_destroy it does not destroy the associated linked_model.

This is because paranoia tries to access the linked model by running self.send(name). This command will not pick up soft-deleted has_one associations (though it works fine for has_many associations) so some extra code is required in this scenario.

Note the reload in the test is required, as otherwise the version of my_model in memory still links to the LinkedModel.