Add a "strike all" option

[stevegrunwell]

For initial installations, clicking "Strike Revisions" over and over with high numbers is a pain. There should be a "clean up everything to this point" option; it won't be used often, but will help people get up and running with the plugin immediately.

This feature should be accessible via Tools > Revision Strike and the WP-CLI command.

[stevegrunwell]

Going through a site with 120k+ revisions, removing them 1000 at a time this feature is definitely necessary. Maybe wire it up to a WP Async Task to prevent timeouts? An email could be triggered once complete or some sort of notification within WordPress (even something as simple as setting an option to notify users of the final results would be sufficient) so users aren't waiting forever for thousands upon thousands of revisions to be cleared out.