Bug fixes

Drupal 9 compatibility,
Blazy 2.0+ deprecated code cleanup,
General code cleanup.

This release addresses issues preventing Drupal 9 support and introduces a Package Source Plugin type, allowing plugins to define behavior specific to different kinds of data sources and the operations required to gather files related to those data sources. New JSON:API and REST Export plugins handle the heavy lifting for each export type now.

This release includes the archive and restore features, which means that the module is now functionally complete. It is also now ready for Drupal 9.

Changes since release alpha6:

This is a beta release for the next major version of Drupal. Drupal 9 beta releases are intended for site owners and module or theme authors to test compatibility and upgrade paths for Drupal 9.0. Beta releases are not intended for production.

Fixes
- #3137146 Rounding issue