Add actionable interface for usage in openhandler

[barryvdh]

Rough prototype of ability to run action through the openhandler. Downside is that collectors do not have access to the Debugbar instance, so not sure how to best generate those links. Would also only be possible to run actions generated by the server, but this is a security enhancement as we want to avoid unsafe actions.

Similar example is running Explain commands https://github.com/barryvdh/laravel-debugbar/pull/1648 and the CacheController https://github.com/barryvdh/laravel-debugbar/blob/master/src/Controllers/CacheController.php