Add optional support for passing datastore encryption key from caller

roles/datastore/tasks/mounts.yaml

@@ -60,6 +60,7 @@
   block:
     - name: Prompt for decryption key
       no_log: true
+      when: skylab_datastore_encryption_password is not defined
       ansible.builtin.pause:
         prompt: >-
           Datastore device {{ inventory_hostname }}:/dev/{{ skylab_datastore_device }} is not
@@ -73,7 +74,7 @@
         device: /dev/{{ skylab_datastore_device }}
         state: opened
         name: brick
-        passphrase: "{{ _luks_decryption_key.user_input }}"
+        passphrase: "{{ _luks_decryption_key.user_input | default(skylab_datastore_encryption_password) }}"
 
     - name: Fetch updated block device information
       ansible.builtin.command: