Move roles/matrix* to roles/custom/matrix*

This paves the way for installing other roles into `roles/galaxy` using `ansible-galaxy`,
similar to how it's done in:

- https://github.com/spantaleev/gitea-docker-ansible-deploy
- https://github.com/spantaleev/nextcloud-docker-ansible-deploy

In the near future, we'll be removing a lot of the shared role code from here
and using upstream roles for it. Some of the core `matrix-*` roles have
already been extracted out into other reusable roles:

- https://github.com/devture/com.devture.ansible.role.postgres
- https://github.com/devture/com.devture.ansible.role.systemd_docker_base
- https://github.com/devture/com.devture.ansible.role.timesync
- https://github.com/devture/com.devture.ansible.role.vars_preserver
- https://github.com/devture/com.devture.ansible.role.playbook_runtime_messages
- https://github.com/devture/com.devture.ansible.role.playbook_help

We just need to migrate to those.

roles/custom/matrix-bot-maubot/tasks/init.yml

@@ -0,0 +1,47 @@
+---
+
+- name: Add maubot to the systemd service list
+  ansible.builtin.set_fact:
+    matrix_systemd_services_list: "{{ matrix_systemd_services_list + ['matrix-bot-maubot.service'] }}"
+  when: matrix_bot_maubot_enabled | bool
+
+- name: Configure nginx for maubot
+  block:
+    - name: Generate Maubot proxying configuration for matrix-nginx-proxy
+      ansible.builtin.set_fact:
+        matrix_bot_maubot_matrix_nginx_proxy_configuration: |
+          location ~ ^/(_matrix/maubot/.*) {
+          {% if matrix_nginx_proxy_enabled | default(False) %}
+            {# Use the embedded DNS resolver in Docker containers to discover the service #}
+             resolver 127.0.0.11 valid=5s;
+             set $backend "matrix-bot-maubot:{{ matrix_bot_maubot_management_interface_port }}";
+             proxy_pass http://$backend$request_uri;
+             proxy_set_header Upgrade $http_upgrade;
+             proxy_set_header Connection "upgrade";
+          {% else %}
+            {# Generic configuration for use outside of our container setup #}
+            proxy_pass http://127.0.0.1:{{ matrix_bot_maubot_management_interface_port }}$request_uri;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection "upgrade";
+          {% endif %}
+          }
+      when: matrix_bot_maubot_proxy_management_interface | bool
+
+    - name: Register Maubot's proxying configuration with matrix-nginx-proxy
+      ansible.builtin.set_fact:
+        matrix_nginx_proxy_proxy_matrix_additional_server_configuration_blocks: |
+          {{
+            matrix_nginx_proxy_proxy_matrix_additional_server_configuration_blocks | default([])
+            +
+            [matrix_bot_maubot_matrix_nginx_proxy_configuration]
+          }}
+      when: matrix_bot_maubot_proxy_management_interface | bool
+
+    - name: Warn about reverse-proxying if matrix-nginx-proxy not used
+      ansible.builtin.debug:
+        msg: >-
+          NOTE: You've enabled Maubot but are not using the matrix-nginx-proxy
+          reverse proxy.
+          Please make sure that you're proxying the `/_matrix/maubot`
+          URL endpoint to the matrix-maubot container.
+      when: "matrix_bot_maubot_enabled | bool and matrix_bot_maubot_proxy_management_interface | bool and matrix_nginx_proxy_enabled is not defined"