Allow the matrix user username and groupname to be configured separately

No migration steps should be required.

roles/matrix-nginx-proxy/tasks/ssl/main.yml

@@ -14,7 +14,7 @@
     state: directory
     mode: 0770
     owner: "{{ matrix_user_username }}"
-    group: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
     recurse: true
   with_items:
     - "{{ matrix_ssl_log_dir_path }}"

roles/matrix-nginx-proxy/tasks/ssl/setup_ssl_self_signed_obtain_for_domain.yml

@@ -17,7 +17,7 @@
     state: directory
     mode: 0750
     owner: "{{ matrix_user_username }}"
-    group: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
   when: "not matrix_ssl_certificate_cert_path_stat_result.stat.exists"
 
 # The proper way to do this is by using a sequence of