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-base/tasks/setup_matrix_base.yml

@@ -0,0 +1,77 @@
+---
+
+- name: Ensure Matrix base path exists
+  ansible.builtin.file:
+    path: "{{ item }}"
+    state: directory
+    mode: "{{ matrix_base_data_path_mode }}"
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+  with_items:
+    - "{{ matrix_base_data_path }}"
+
+- name: Preserve vars.yml on the server for easily restoring if it gets lost later on
+  ansible.builtin.copy:
+    src: "{{ matrix_vars_yml_snapshotting_src }}"
+    dest: "{{ matrix_base_data_path }}/vars.yml"
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+    mode: '0660'
+  when: "matrix_vars_yml_snapshotting_enabled | bool"
+
+- name: Save current git-repo status on the target to aid with restoring in case of problems
+  when: "matrix_playbook_commit_hash_preservation_enabled|bool"
+  block:
+    - name: Get local git hash  # noqa command-instead-of-module
+      delegate_to: 127.0.0.1
+      become: false
+      register: git_describe
+      changed_when: false
+      ansible.builtin.shell:
+        git describe
+            --always
+            --tags
+            --dirty
+            --long
+            --all
+
+    - ansible.builtin.set_fact:
+        git_hash: "{{ git_describe.stdout }}"
+
+    - name: Git hash
+      ansible.builtin.debug:
+        msg: "Git hash: {{ git_hash }}"
+
+    - name: Save git_hash.yml on target
+      ansible.builtin.copy:
+        content: "{{ git_hash }}"
+        dest: "{{ matrix_base_data_path }}/git_hash.yml"
+        owner: "{{ matrix_user_username }}"
+        group: "{{ matrix_user_groupname }}"
+        mode: '0660'
+
+  rescue:
+    - name: GIT not found error
+      ansible.builtin.debug:
+        msg: >-
+          Couldn't find GIT on the local machine. Continuing without saving the GIT hash.
+          You can disable saving the GIT hash by setting 'matrix_playbook_commit_hash_preservation_enabled: false' in vars.yml
+      when: "git_describe.stderr.find('git: not found') != -1"
+
+    - name: Get GIT hash error
+      ansible.builtin.fail:
+        msg: >-
+          Error when trying to get the GIT hash. Please consult the error message above.
+          You can disable saving the GIT hash by setting 'matrix_playbook_commit_hash_preservation_enabled: false' in vars.yml
+      when: "git_describe.stderr.find('git: not found') == -1"
+
+- name: Ensure Matrix network is created in Docker
+  community.docker.docker_network:
+    name: "{{ matrix_docker_network }}"
+    driver: bridge
+
+- name: Ensure matrix-remove-all script created
+  ansible.builtin.template:
+    src: "{{ role_path }}/templates/usr-local-bin/matrix-remove-all.j2"
+    dest: "{{ matrix_local_bin_path }}/matrix-remove-all"
+    mode: 0750