Add Lesson widgets for Elementor

**Is your feature request related to a problem? Please describe.**
There's currently no "Lesson Progression (Mark Complete)" widget nor "Lesson Navigation" widget for Elementor

**Describe the solution you'd like**
Add these widgets, and next time a lesson is edited in Elementor "migrate" the lesson to a) add those elementor widgets at the bottom of a lesson and b) prevent the defaults from showing. This is similar to what happens when editing a course.