k8up support

We now have full k8up support, also for the newest release with individual S3 Buckets per Lagoon Project. So far we already supported k8up, but only the global S3 bucket system. Which unfortunately is not really usable in very big cluster with thousand of backups.

Beside of that we also have:

Features:

• Add a PROJECT_SECRET which injects a random secret into all environment which is the same across all Lagoon Projects. (#947)

Changes:

• Downgraded the mariadb-client/mysql-client in the php-cli images from MariaDB 10.3 to 10.2 as there is a bug that prevents mysqldump to run against non mariadb 10.3 servers (4913081 - https://jira.mariadb.org/browse/MDEV-17429)

Bugfixes:

• Fix the start of RabbitMQ Cluster with non standard service names (#937)
• Force deprovisioning of "Provisioned Services" when deleting environments (#939)

Improvements:

• Allow certain Lagoon tasks to be disabled in the UI via the environment variable LAGOON_UI_TASK_BLACKLIST (#946)

Documentation:

• Code Standard improvement of the Drupal example files in Lagoon (#938) thank you @dan2k3k4