add borg backup (#1727)

* add borg backup

* lint fix

* add exlclude patterns

* missed in the #1726 fix for honoroit

* feedback

* Fix indentation

* feedback

* feedback

* feedback

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

roles/matrix-backup-borg/tasks/validate_config.yml

@@ -0,0 +1,10 @@
+---
+- name: Fail if required settings not defined
+  fail:
+    msg: >-
+      You need to define a required configuration setting (`{{ item }}`).
+  when: "vars[item] == ''"
+  with_items:
+    - "matrix_backup_borg_ssh_key_private"
+    - "matrix_backup_borg_location_repositories"
+    - "matrix_backup_borg_storage_encryption_passphrase"