Add option :all_app_last to stylesheet_link_tag helper

[dari-us]

We have tens of apps in our company that all use stylesheets from a common corporate design layout gem.
In some of these apps, custom styles are used, which partly overwrite existing styles from the layout gem.

However, without CSS bundling (which we intend to avoid), there is no clean way to ensure the app styles overwrite the styles from vendor and the gems (aka are loaded last).
The only obscure way is to name all local files like zzzzzzzz_application.css to make those last in the list generated by stylesheet_link_tag :all.

To remedy this, I have added the option :all_app_last so the stylesheet tags are generated vendor and gems first, app last so external styles can safely be overwritten in stylesheets under app/assets.

Is this feature desireable for a broader audience or is something like this already possible and I just missed it?