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/test_snapshot_clobber.yml

@@ -0,0 +1,41 @@
+---
+# 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 a snapshot, overwriting if one already exists at path
+  block:
+  - name: Create a snapshot named 'snapshot_clobber'
+    community.general.btrfs_subvolume:
+      automount: Yes
+      filesystem_label: "{{ btrfs_subvolume_target_label }}"
+      name: "/snapshot_clobber"
+      snapshot_source: "/"
+      snapshot_conflict: "clobber"
+      state: "present"
+    register: result
+  - name: Snapshot 'snapshot_clobber' created
+    ansible.builtin.assert:
+      that:
+      - result is changed
+
+  - name: Create a snapshot named 'snapshot_clobber' (no idempotency)
+    community.general.btrfs_subvolume:
+      automount: Yes
+      filesystem_label: "{{ btrfs_subvolume_target_label }}"
+      name: "/snapshot_clobber"
+      snapshot_source: "/"
+      snapshot_conflict: "clobber"
+      state: "present"
+    register: result
+  - name: Snapshot 'snapshot_clobber' created (no idempotency)
+    ansible.builtin.assert:
+      that:
+      - result is changed
+
+- name: Cleanup created snapshot
+  community.general.btrfs_subvolume:
+    automount: Yes
+    filesystem_label: "{{ btrfs_subvolume_target_label }}"
+    name: "/snapshot_clobber"
+    state: "absent"