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/templates/synapse/ext/s3-storage-provider/usr-local-bin/matrix-synapse-s3-storage-provider-migrate.j2

@@ -0,0 +1,13 @@
+#jinja2: lstrip_blocks: "True"
+#!/bin/bash
+
+{{ matrix_host_command_docker }} run \
+	--rm \
+	--env-file={{ matrix_synapse_ext_s3_storage_provider_path }}/env \
+	--mount type=bind,src={{ matrix_synapse_storage_path }},dst=/matrix-media-store-parent,bind-propagation=slave \
+	--mount type=bind,src={{ matrix_synapse_ext_s3_storage_provider_path }}/data,dst=/data \
+	--workdir=/data \
+	--network={{ matrix_docker_network }} \
+	--entrypoint=/bin/bash \
+	{{ matrix_synapse_docker_image_final }} \
+	-c 's3_media_upload update-db $UPDATE_DB_DURATION && s3_media_upload --no-progress check-deleted $MEDIA_PATH && s3_media_upload --no-progress upload $MEDIA_PATH $BUCKET --delete --storage-class $STORAGE_CLASS --endpoint-url $ENDPOINT'

roles/custom/matrix-synapse/templates/synapse/ext/s3-storage-provider/usr-local-bin/matrix-synapse-s3-storage-provider-shell.j2

@@ -0,0 +1,13 @@
+#jinja2: lstrip_blocks: "True"
+#!/bin/bash
+
+{{ matrix_host_command_docker }} run \
+	-it \
+	--rm \
+	--env-file={{ matrix_synapse_ext_s3_storage_provider_path }}/env \
+	--mount type=bind,src={{ matrix_synapse_storage_path }},dst=/matrix-media-store-parent,bind-propagation=slave \
+	--mount type=bind,src={{ matrix_synapse_ext_s3_storage_provider_path }}/data,dst=/data \
+	--workdir=/data \
+	--network={{ matrix_docker_network }} \
+	--entrypoint=/bin/bash \
+	{{ matrix_synapse_docker_image_final }}