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-mautrix-facebook/tasks/validate_config.yml

@@ -0,0 +1,24 @@
+---
+
+- name: Fail if required settings not defined
+  ansible.builtin.fail:
+    msg: >-
+      You need to define a required configuration setting (`{{ item }}`).
+  when: "vars[item] == ''"
+  with_items:
+    - "matrix_mautrix_facebook_public_endpoint"
+    - "matrix_mautrix_facebook_appservice_token"
+    - "matrix_mautrix_facebook_homeserver_token"
+
+- when: "matrix_mautrix_facebook_database_engine == 'sqlite' and matrix_mautrix_facebook_docker_image.endswith(':da1b4ec596e334325a1589e70829dea46e73064b')"
+  block:
+    - name: Inject warning if on an old SQLite-supporting version
+      ansible.builtin.set_fact:
+        matrix_playbook_runtime_results: |
+          {{
+            matrix_playbook_runtime_results | default([])
+            +
+            [
+              "NOTE: Your mautrix-facebook bridge is still on SQLite and on the last version that supported it, before support was dropped. Support has been subsequently re-added in v0.3.2, so we advise you to upgrade (by removing your `matrix_mautrix_facebook_docker_image` definition from vars.yml)"
+            ]
+          }}