Upgrade Dendrite (0.3.11 -> 0.5.0) and update configuration

This brings dendrite.yaml up to date and cleans things up a bit.

roles/matrix-dendrite/tasks/dendrite/setup_install.yml

@@ -36,7 +36,7 @@
   command: |
     docker run
     --rm
-    --name=matrix-config
+    --name=matrix-dendrite-config
     --entrypoint=generate-keys
     --mount type=bind,src={{ matrix_dendrite_config_dir_path }},dst=/data
     {{ matrix_dendrite_docker_image }} --private-key=/data/{{ matrix_server_fqn_matrix }}.signing.pem

roles/matrix-dendrite/tasks/validate_config.yml

@@ -5,7 +5,8 @@
       You need to define a required configuration setting (`{{ item }}`) for using Dendrite.
   when: "vars[item] == ''"
   with_items:
-    - "matrix_dendrite_macaroon_secret_key"
+    - "matrix_dendrite_generic_secret_key"
+    - "matrix_dendrite_registration_shared_secret"
 
 - name: (Deprecation) Catch and report renamed settings
   fail: