Install _RbsRailsPathHelpers to ActionController::Base by default

[tk0miya]

Inside ActionController, the application routes are installed to the ActionController::Base class on bootstrap automatically.

To follow the behavior, it's better to install _RbsRailsPathHelpers to ActionController::Base by default.

refs:

• https://github.com/rails/rails/blob/v7.2.1/actionpack/lib/action_controller/railtie.rb#L75
• https://github.com/rails/rails/blob/v7.2.1/actionpack/lib/abstract_controller/railties/routes_helpers.rb#L18

Note: this includes https://github.com/pocke/rbs_rails/pull/274.