[XB] Lessons 2.0.3

We now have a live demo! https://demo.xenbaker.com/lessons/

New Features:​

• Added separate permissions for viewing unapproved/deleted, undeleting and approving/unapproving classrooms
• Added new lesson inline moderation tool: move lessons to another classroom
• Added ability to delete classroom enrolls and lesson completions from public interface
• Added filter by username on classroom and lesson completions list in public interface
• Added new statistics to Lessons statistics widget: Unique students, lessons complete
• Added options to control results per page on classroom enrolls/completions, lesson completions
• Added icons on action buttons for more intuitive navigation
• Added page criteria support
• Added support for uploading webp thumbnails for lessons and classrooms
• Added ability to reassign classrooms
• Added ability to move classroom directly from classroom page
• Setup default permissions on first install

Fixes:​

• Fixed incorrect classroom breadcrumbs on lesson add page
• Fixed incorrect URL in classroom completions list page nav
• Fixed awaiting approval lessons is not shown after adding for lesson author
• Fixed incorrect service classname throwing error when approving lesson
• Added missing phrases: "You must complete previous lesson", "Approve lesson"