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/import_media_store.yml

@@ -0,0 +1,84 @@
+---
+
+# Pre-checks
+
+- name: Fail if playbook called incorrectly
+  ansible.builtin.fail:
+    msg: "The `server_path_media_store` variable needs to be provided to this playbook, via --extra-vars"
+  when: "server_path_media_store is not defined or server_path_media_store.startswith('<')"
+
+- name: Fail if media store is on Amazon S3
+  ansible.builtin.fail:
+    msg: "Your media store is on Amazon S3. Due to technical limitations, restoring is not supported."
+  when: matrix_s3_media_store_enabled | bool
+
+- name: Check if the provided media store directory exists
+  ansible.builtin.stat:
+    path: "{{ server_path_media_store }}"
+  register: server_path_media_store_stat
+
+- name: Fail if provided media store directory doesn't exist on the server
+  ansible.builtin.fail:
+    msg: "{{ server_path_media_store }} cannot be found on the server"
+  when: "not server_path_media_store_stat.stat.exists or not server_path_media_store_stat.stat.isdir"
+
+- name: Check if media store contains local_content
+  ansible.builtin.stat:
+    path: "{{ server_path_media_store }}/local_content"
+  register: server_path_media_store_local_content_stat
+
+- name: Check if media store contains remote_content
+  ansible.builtin.stat:
+    path: "{{ server_path_media_store }}/remote_content"
+  register: server_path_media_store_remote_content_stat
+
+- name: Fail if media store directory doesn't look okay (lacking remote and local content)
+  ansible.builtin.fail:
+    msg: "{{ server_path_media_store }} contains neither local_content nor remote_content directories. It's most likely a mistake and is not a media store directory."
+  when: "not server_path_media_store_local_content_stat.stat.exists and not server_path_media_store_remote_content_stat.stat.exists"
+
+
+# Actual import work
+
+- name: Ensure matrix-synapse is stopped
+  ansible.builtin.service:
+    name: matrix-synapse
+    state: stopped
+    enabled: false
+    daemon_reload: true
+  register: stopping_result
+
+# This can only work with local files, not if the media store is on Amazon S3,
+# as it won't be accessible in such a case.
+- name: Ensure provided media store directory is synchronized
+  ansible.posix.synchronize:
+    src: "{{ server_path_media_store }}/"
+    dest: "{{ matrix_synapse_media_store_path }}"
+    delete: true
+    # It's wasteful to preserve owner/group now. We chown below anyway.
+    owner: false
+    group: false
+    times: true
+  delegate_to: "{{ inventory_hostname }}"
+
+# This is for the generic case and fails in other cases (remote file systems),
+# because in such cases the base path (matrix_synapse_media_store_path) is a mount point.
+- name: Ensure media store permissions are correct (generic case)
+  ansible.builtin.file:
+    path: "{{ matrix_synapse_media_store_path }}"
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+    recurse: true
+  when: "not matrix_s3_media_store_enabled | bool"
+
+# We don't chown for Goofys, because due to the way it's mounted,
+# all files become owned by whoever needs to own them.
+
+- name: Ensure Synapse is started (if it previously was)
+  ansible.builtin.service:
+    name: "{{ item }}"
+    state: started
+    daemon_reload: true
+  when: "stopping_result.changed"
+  with_items:
+    - matrix-synapse