Add a 'litestream' backup type

.gitlab-ci.yml

docs/reference.md

docs/reference.pdf

roles/float-base-datasets/files/float-dataset-restore

roles/float-base-datasets/tasks/dataset.yml

roles/float-base-datasets/tasks/dataset_litestream.yml

roles/float-base-datasets/tasks/dataset_tabacco.yml

roles/float-base-datasets/tasks/main.yml

roles/float-base-datasets/templates/litestream-env.j2

...t-base-datasets/templates/litestream-replicate-service.j2

...loat-base-datasets/templates/litestream-restore-script.j2

roles/float-base-datasets/templates/restore-service.j2

...s/float-base-datasets/templates/tabacco-restore-script.j2

roles/float-base/tasks/apt.yml

test/backup.ref/config-backup.yml

test/backup.ref/passwords.yml

test/backup.ref/services.yml

test/backup.ref/site.yml