LearnDash LMS 4.21.1

* Feature - Add course completion page.
* Tweak - Updated course progression to flow as expected between steps in a course.
* Fix - Lesson not marking as complete when "Not Graded, full points awarded" option set in quiz essay type.
* Fix - Added additional validation for shortcodes and blocks.
* Tweak - Added filters: `learndash_course_completion_page_redirect_enabled`, `learndash_course_linear_step_ids`, `learndash_course_next_step_default_value`, `learndash_course_next_step_id`, `learndash_course_next_step_url`, `learndash_course_previous_step_default_value`, `learndash_course_previous_step_id`, `learndash_course_previous_step_url`, `learndash_course_step_completion_url`.
* Tweak - Updated filters: `learndash_course_completion_url`, `learndash_next_post_link`, `learndash_previous_post_link`.
* Tweak - Deprecated filters: `learndash_completion_redirect`, `learndash_show_parent_next_link`, `learndash_show_parent_previous_link`.
* Tweak - Added functions: `learndash_course_get_completion_url`, `learndash_course_get_linear_step_ids`, `learndash_course_get_step_completion_url`, `learndash_course_steps_requires_watching_video_after_sub_steps`.
* Tweak - Updated functions: `learndash_approve_assignment`, `learndash_get_step_post_statuses`, `learndash_mark_complete_process`, `learndash_next_post_link`, `learndash_previous_post_link`, `learndash_process_mark_complete`, `learndash_quiz_continue_link`, `learndash_quiz_redirect`, `learndash_upload_assignment_init`.
* Tweak - Deprecated functions: `learndash_ajax_mark_complete`, `learndash_course_progress_widget`, `learndash_get_next_lesson_redirect`, `learndash_next_global_quiz`, `learndash_next_lesson_quiz`, `learndash_update_completion`.
* Tweak - Updated templates: `ld30/templates/modules/course-steps.php`.

* Fix - User's essays and assignments posts do not get deleted permanently when the data erasure request is executed.
* Security - Tightened security around REST API.
* Security - Tightened security around assignments & essays files.
* Tweak - Changed assignment files uploading path to `uploads/learndash/assignments`.
* Tweak - Changed essay files uploading path to `uploads/learndash/essays`.
* Tweak - Made essay and assignment file links dynamic.
* Tweak - Added filters: `learndash_file_can_be_downloaded`, `learndash_file_protection_paths`.
* Tweak - Added functions: `learndash_assignment_get_download_url`, `learndash_quiz_essay_get_download_url`.
* Tweak - Deprecated classes: `LD_REST_Posts_Gutenberg_Controller`.
* Tweak - Deprecated filters: `learndash_rest_wp_archive_repsonse`, `learndash_rest_wp_archive_viewable`.
* Tweak - Updated filters: `learndash_assignment_process_init`, `learndash_essay_upload_dirbase`, `learndash_essay_upload_urlbase`, `learndash_fileupload_process`, `learndash_upload_assignment_init`.
* Tweak - Updated functions: , `learndash_add_new_essay_response`, `learndash_before_delete_essay`, `learndash_delete_user_data`, `learndash_essay_fileupload_process`, `learndash_essay_permissions`.
* Tweak - Updated templates: `ld30/templates/assignment/partials/row.php`, `ld30/templates/shortcodes/profile/assignment-row.php`, `themes/legacy/templates/learndash_lesson_assignment_uploads_list.php`.

4.10.2