Add support for more flexible container port exposing

Fixes #171 (Github Issue).

roles/matrix-dimension/tasks/validate_config.yml

@@ -13,3 +13,12 @@
   with_items:
     - "matrix_synapse_federation_enabled"
   when: "matrix_dimension_enabled|bool and not matrix_synapse_federation_enabled|bool"
+
+- name: (Deprecation) Catch and report renamed Dimension variables
+  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_dimension_container_expose_port', 'new': '<superseded by matrix_dimension_container_http_host_bind_port>'}