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-jitsi/tasks/setup_jitsi_base.yml

@@ -0,0 +1,22 @@
+---
+
+- ansible.builtin.import_tasks: "{{ role_path }}/../matrix-base/tasks/util/ensure_openssl_installed.yml"
+
+#
+# Tasks related to setting up jitsi
+#
+
+- name: Ensure Matrix jitsi base path exists
+  ansible.builtin.file:
+    path: "{{ item.path }}"
+    state: directory
+    mode: 0750
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+  with_items:
+    - {path: "{{ matrix_jitsi_base_path }}", when: true}
+  when: matrix_jitsi_enabled | bool and item.when
+
+#
+# Tasks related to getting rid of jitsi (if it was previously enabled)
+#