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-prometheus-postgres-exporter/tasks/setup.yml

@@ -0,0 +1,59 @@
+---
+
+#
+# Tasks related to setting up matrix-prometheus-postgres-exporter
+#
+
+- name: Ensure matrix-prometheus-postgres-exporter image is pulled
+  community.docker.docker_image:
+    name: "{{ matrix_prometheus_postgres_exporter_docker_image }}"
+    source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
+    force_source: "{{ matrix_prometheus_postgres_exporter_docker_image_force_pull if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
+    force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_prometheus_postgres_exporter_docker_image_force_pull }}"
+  when: "matrix_prometheus_postgres_exporter_enabled | bool"
+  register: result
+  retries: "{{ matrix_container_retries_count }}"
+  delay: "{{ matrix_container_retries_delay }}"
+  until: result is not failed
+
+- name: Ensure matrix-prometheus-postgres-exporter.service installed
+  ansible.builtin.template:
+    src: "{{ role_path }}/templates/systemd/matrix-prometheus-postgres-exporter.service.j2"
+    dest: "{{ matrix_systemd_path }}/matrix-prometheus-postgres-exporter.service"
+    mode: 0644
+  register: matrix_prometheus_postgres_exporter_systemd_service_result
+  when: matrix_prometheus_postgres_exporter_enabled | bool
+
+- name: Ensure systemd reloaded after matrix-prometheus.service installation
+  ansible.builtin.service:
+    daemon_reload: true
+  when: "matrix_prometheus_postgres_exporter_enabled | bool and matrix_prometheus_postgres_exporter_systemd_service_result.changed"
+
+#
+# Tasks related to getting rid of matrix-prometheus-postgres-exporter (if it was previously enabled)
+#
+
+- name: Check existence of matrix-prometheus-postgres-exporter service
+  ansible.builtin.stat:
+    path: "{{ matrix_systemd_path }}/matrix-prometheus-postgres-exporter.service"
+  register: matrix_prometheus_postgres_exporter_service_stat
+
+- name: Ensure matrix-prometheus-postgres-exporter is stopped
+  ansible.builtin.service:
+    name: matrix-prometheus-postgres-exporter
+    state: stopped
+    enabled: false
+    daemon_reload: true
+  register: stopping_result
+  when: "not matrix_prometheus_postgres_exporter_enabled | bool and matrix_prometheus_postgres_exporter_service_stat.stat.exists"
+
+- name: Ensure matrix-prometheus-postgres-exporter.service doesn't exist
+  ansible.builtin.file:
+    path: "{{ matrix_systemd_path }}/matrix-prometheus-postgres-exporter.service"
+    state: absent
+  when: "not matrix_prometheus_postgres_exporter_enabled | bool and matrix_prometheus_postgres_exporter_service_stat.stat.exists"
+
+- name: Ensure systemd reloaded after matrix-prometheus-postgres-exporter.service removal
+  ansible.builtin.service:
+    daemon_reload: true
+  when: "not matrix_prometheus_postgres_exporter_enabled | bool and matrix_prometheus_postgres_exporter_service_stat.stat.exists"