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-synapse/tasks/ext/encryption-disabler/setup_install.yml

@@ -0,0 +1,41 @@
+---
+
+- name: Download matrix_encryption_disabler
+  ansible.builtin.get_url:
+    url: "{{ matrix_synapse_ext_encryption_disabler_download_url }}"
+    dest: "{{ matrix_synapse_ext_path }}/matrix_e2ee_filter.py"
+    force: true
+    mode: 0440
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+  register: result
+  retries: "{{ matrix_geturl_retries_count }}"
+  delay: "{{ matrix_geturl_retries_delay }}"
+  until: result is not failed
+
+- ansible.builtin.set_fact:
+    matrix_synapse_modules: |
+      {{
+        matrix_synapse_modules | default([])
+        +
+        [
+          {
+            "module": "matrix_e2ee_filter.EncryptedRoomFilter",
+            "config": matrix_synapse_ext_encryption_config
+          }
+        ]
+      }}
+
+    matrix_synapse_container_extra_arguments: >
+      {{
+        matrix_synapse_container_extra_arguments | default([])
+        +
+        ["--mount type=bind,src={{ matrix_synapse_ext_path }}/matrix_e2ee_filter.py,dst={{ matrix_synapse_in_container_python_packages_path }}/matrix_e2ee_filter.py,ro"]
+      }}
+
+    matrix_synapse_additional_loggers: >
+      {{
+        matrix_synapse_additional_loggers
+        +
+        [{'name': 'matrix_e2ee_filter', 'level': 'INFO'}]
+      }}