New modules btrfs_subvolume / btrfs_info (#5832)

* Initial implementation for new modules btrfs_subvolume and btrfs_info

* Improve/flesh out documentation. Add ability to target filesystem by uuid, label or device. Update tests to test targeting filesystem by each supported parameter and when only mountpoint.

* Updates for btrfs modules. Add missing copyright notices. Switch options to contains in return documentation. Update btrfs_subvolume to always use closest parent mount.

* Add maintainers for btrfs module(s) and remove unused class member cause lint failure.

* Add changelog fragment. Attempt to only run against the VMs as part of CI.

* Updates per code review. Remove changelog fragment. Switch use of map to list comprehension. Add trailing comma to last item in multi-line dicts. Clean up documentation with complete senstences for descriptions and correct/consistent use of macros.

* Improved error handling in btrfs_subvolume module: add custom exception type, favor exceptions over immediate call to fail_json and add single top level return for failure scenarios. Normalize name and snapshot_source parameters early in module execution and remove unecessary duplicate normalization throughout processing.

* Add azp/posix/3 to aliases per feedback

* Clean up automatic mounting. Prevent automount when check_mode=True. Immediately fail if a mount is identified as required and automount=True. Identify the minimal subset of subvolumes that need to be mounted instead of just finding a single common root.

* Skip btrfs_subvolume integration tests if btrfs-progs isn't successfully installed.

* Bump version_added for btrfs modules to 6.6.0. Ensure consistent trailing punctuation for module descriptions and document check_mode behavior as attribute description rather than a module level note.

* Remove unused imports from btrfs_subvolume module.

* Fix import.

* Docs improvements.

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

tests/integration/targets/btrfs_subvolume/tasks/setup.yml

@@ -0,0 +1,37 @@
+---
+# Copyright (c) 2022, Gregory Furlong <gnfzdz@fzdz.io>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+- name: "Create file {{ item.file }} to back loop device {{ item.loop }}"
+  ansible.builtin.command:
+    cmd: "dd if=/dev/zero of={{ item.file }} bs=1M count=200"  ## minimum count 109
+    creates: "{{ item.file }}"
+  with_items: "{{ btrfs_subvolume_configs }}"
+
+- name: "Setup loop device {{ item.loop }}"
+  ansible.builtin.command:
+    cmd: "losetup {{ item.loop }} {{ item.file }}"
+    creates: "{{ item.loop }}"
+  with_items: "{{ btrfs_subvolume_configs }}"
+
+- name: Create single device btrfs filesystem
+  ansible.builtin.command:
+    cmd: "mkfs.btrfs --label {{ btrfs_subvolume_single_label }} -f {{ btrfs_subvolume_single_devices | first }}"
+  changed_when: True
+
+- name: Create multiple device btrfs filesystem
+  ansible.builtin.command:
+    cmd: "mkfs.btrfs --label {{ btrfs_subvolume_multiple_label }} -f -d raid0 {{ btrfs_subvolume_multiple_devices | join(' ') }}"
+  changed_when: True
+
+# Typically created by udev, but apparently missing on Alpine
+- name: Create btrfs control device node
+  ansible.builtin.command:
+    cmd: "mknod /dev/btrfs-control c 10 234"
+    creates: "/dev/btrfs-control"
+
+- name: Force rescan to ensure all device are detected
+  ansible.builtin.command:
+    cmd: "btrfs device scan"
+  changed_when: True