This adds support for a style wherein the concept of a module
used as a namespace is kept separate from the definition of a
class or module itself.

Since the introduction of Zeitwerk in Rails the benefits of
retaining the nested style in terms of accurate constant lookup have
disappeared.

This makes the compact style seem appealing for the following
reasons:

* Less low information value horizontal whitespace.
* Less git churn when moving files around between differing namespace depths.
* Easier scanning on the eyes when looking for the main constant.

The compact style suffers slightly from the following though:
* Main constant definition in a file is far over to the right in heavily namespaced files.
* Change to either the namespace or the constant name results in change to the same line.

The new proposed namespace style allows for
* Conceptual separation of the namespace/package concept from the class or
   module definition.
* File move refactors to a different namespace result in a diff that only touches
the namespace constant part of the file.
* Scanning by eye for the constant name is easier.

```ruby
module Foo
  module Bar
    module Baz
      module Qux
        module Quux
          module Quuz
            module Corge
              module Grault
                module Garply
                  module Waldo
                    module Fred
                      class Plugh
                      end
                    end
                  end
                end
              end
            end
          end
        end
      end
    end
  end
end
```

```ruby
module Foo::Bar::Baz::Qux::Quux::Quuz::Corge::Grault::Garply::Waldo::Fred
  class Plugh
  end
end
```

```ruby
class Foo::Bar::Baz::Qux::Quux::Quuz::Corge::Grault::Garply::Waldo::Fred::Plugh
end
```