Add new action to register custom Elementor endpoints

Prerequisites • I have searched for similar feature requests in both open and closed discussions and cannot find an existing request. • I have verified that the feature is still missing from the latest stable versions of Elementor or Elementor Pro. What problem is your feature request going to solve? Please describe.. Elementor's regex for their global colors and typography endpoints don't allow hyphens or underscores in the global property ID, as they are currently randomly generated strings (check #12571 ). This makes difficult for advanced users with CSS knowledge to reuse the global color variables. I am developing a solution to use user-defined IDs instead of random strings, which is already working and doesn't cause any issues with Elementor. However, the implementation could be much better if I could make use of Elementor's existing classes. The requested action hook is necessary in order to extend the existing endpoint classes an…