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-appservice-webhooks/tasks/validate_config.yml

@@ -14,3 +14,12 @@
     - matrix_appservice_webhooks_container_network
     - matrix_appservice_webhooks_hostname
     - matrix_appservice_webhooks_path_prefix
+
+- name: (Deprecation) Catch and report renamed appservice-webhooks variables
+  ansible.builtin.fail:
+    msg: >-
+      Your configuration contains a variable, which now has a different name.
+      Please change your configuration to rename the variable (`{{ item.old }}` -> `{{ item.new }}`).
+  when: "item.old in vars"
+  with_items:
+    - {'old': 'matrix_appservice_webhooks_docker_image_name_prefix', 'new': 'matrix_appservice_webhooks_docker_image_registry_prefix'}