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-bridge-mx-puppet-discord/tasks/setup_uninstall.yml

@@ -0,0 +1,25 @@
+---
+
+- name: Check existence of matrix-mx-puppet-discord service
+  ansible.builtin.stat:
+    path: "/etc/systemd/system/matrix-mx-puppet-discord.service"
+  register: matrix_mx_puppet_discord_service_stat
+
+- name: Ensure matrix-mx-puppet-discord is stopped
+  ansible.builtin.service:
+    name: matrix-mx-puppet-discord
+    state: stopped
+    enabled: false
+    daemon_reload: true
+  when: "matrix_mx_puppet_discord_service_stat.stat.exists"
+
+- name: Ensure matrix-mx-puppet-discord.service doesn't exist
+  ansible.builtin.file:
+    path: "/etc/systemd/system/matrix-mx-puppet-discord.service"
+    state: absent
+  when: "matrix_mx_puppet_discord_service_stat.stat.exists"
+
+- name: Ensure systemd reloaded after matrix-mx-puppet-discord.service removal
+  ansible.builtin.service:
+    daemon_reload: true
+  when: "matrix_mx_puppet_discord_service_stat.stat.exists"