Rework all roles to include component_(docker|container)_image_registry_prefix* variables

This:

- brings consistency - no more mixing `_name_prefix` and `_registry_prefix`
- adds extensibility - a future patch will allow reconfiguring all registry prefixes for all roles in the playbook

We still have `_docker_` vs `_container_` inconsistencies.
These may be worked on later.

roles/custom/matrix-bridge-beeper-linkedin/tasks/validate_config.yml

@@ -20,3 +20,4 @@
   when: "item.old in vars"
   with_items:
     - {'old': 'matrix_beeper_linkedin_login_shared_secret', 'new': '<superseded by matrix_beeper_linkedin_bridge_login_shared_secret_map_*>'}
+    - {'old': 'matrix_beeper_linkedin_docker_image_name_prefix', 'new': 'matrix_beeper_linkedin_docker_image_registry_prefix'}