* Offline enhancements (#145)

* Remove backend-based locking implementation. (#142)

* Remove backend-based locking implementation.

This allows for offline usage of courses when progress is enabled.

* Link to the course finish URL directly (#143)

* [#180961256] Link to the course finish URL directly.

* Support lessons progress offline (#144)

* Move progress logic to the frontend.

* Fixed course locking.

* Fixed code checks.

* Simplify check between server and client progress.

Co-authored-by: Kate <kalabro@ya.ru>

Co-authored-by: Kate <kalabro@ya.ru>

* Add new DownloadCoursePopup component (#146)

* [#180885915] Add new DownloadCourseComponent

* Add info about audio files in a course

* Handle syncronizing status

* Add changelog entries.

* Adjust popup styling.

* Style adjustments.

* Added support for service worker customisations (#150)

* Added support for service worker customisations.

* Do not download the same URL multiple times.

* Improve regexp handling in DownloadCoursePopup.

* Add a new isCompletedByUser helper method. (#148)

* Add date tracking for when a lesson is completed. (#149)

* Add a new isCompletedByUser helper method.

* Add date tracking for when a lesson is completed.

Co-authored-by: Kate <kalabro@ya.ru>

* Remove unnecessary coma.

* Switch to the new offline download button but make automated popup disabled by default. Offline audio improvements.

* Allow to override pages/lesson/index file.

* Disable offline detection poling as it's outdated and generates false positives.

Co-authored-by: Rodrigo <rodrigo@systemseed.com>

Co-authored-by: Rodrigo <rodrigo@systemseed.com>
Co-authored-by: Rodrigo Aguilera <hi@rodrigoaguilera.net>

* Prepare 2.5.0-alpha.

* Clean up progress work.

* Fixed JS build.

* Added drupal/pwa in composer suggestions.

* Add a note about PWA in README.md.

* Remove unused var.

Co-authored-by: Rodrigo <rodrigo@systemseed.com>
Co-authored-by: Rodrigo Aguilera <hi@rodrigoaguilera.net>