Feature dismiss

This is the feature for dismissible alerts, as discussed here: https://github.com/wet-boew/wet-boew/issues/5605. You can test it here:
http://wet-boew.pacoup.com/demos/dismiss/dismiss-en.html

There's gonna be docs on wet-boew-styleguide for this (https://github.com/wet-boew/wet-boew-styleguide/pull/200), but for now, there's the dismiss-en.hbs for the sample.

Unit tests incoming in another PR.

**Note:** This feature impacts bootstrap-overrides and normalizes the way details/summary polyfills are rendered compared to native support (i.e. Chrome) and ensures it all works well when combining with alerts.