Migrate and refactor files and repo targets to unified backups

gems/gitlab-backup-cli/lib/gitlab/backup/cli.rb

...itlab-backup-cli/lib/gitlab/backup/cli/backup_executor.rb

...ackup-cli/lib/gitlab/backup/cli/context/source_context.rb

gems/gitlab-backup-cli/lib/gitlab/backup/cli/errors.rb

...up-cli/lib/gitlab/backup/cli/errors/file_restore_error.rb

...p-cli/lib/gitlab/backup/cli/errors/gitaly_backup_error.rb

gems/gitlab-backup-cli/lib/gitlab/backup/cli/repo_type.rb

...tlab-backup-cli/lib/gitlab/backup/cli/restore_executor.rb

gems/gitlab-backup-cli/lib/gitlab/backup/cli/targets.rb

...tlab-backup-cli/lib/gitlab/backup/cli/targets/database.rb

.../gitlab-backup-cli/lib/gitlab/backup/cli/targets/files.rb

...backup-cli/lib/gitlab/backup/cli/targets/gitaly_backup.rb

...backup-cli/lib/gitlab/backup/cli/targets/gitaly_client.rb

...li/lib/gitlab/backup/cli/targets/object_storage/google.rb

...-backup-cli/lib/gitlab/backup/cli/targets/repositories.rb

...gitlab-backup-cli/lib/gitlab/backup/cli/targets/target.rb

...itlab-backup-cli/lib/gitlab/backup/cli/tasks/artifacts.rb

gems/gitlab-backup-cli/lib/gitlab/backup/cli/tasks/builds.rb

...backup-cli/lib/gitlab/backup/cli/tasks/ci_secure_files.rb

...gitlab-backup-cli/lib/gitlab/backup/cli/tasks/database.rb