filesystem: revamp module (#2472)

* revamp filesystem module to prepare next steps

* pass all commands to module.run_command() as lists
* refactor grow() and grow_cmd() to not need to override them so much
* refactor all existing get_fs_size() overrides to raise a ValueError if
  not able to parse command output and return an integer.
* override MKFS_FORCE_FLAGS the same way for all fstypes that require it
* improve documentation of limitations of the module regarding FreeBSD
* fix indentation in DOCUMENTATION
* add/update function/method docstrings
* fix pylint hints

filesystem: refactor integration tests

* Include *reiserfs* and *swap* in tests.
* Fix reiserfs related code and tests accordingly.
* Replace "other fs" (unhandled by this module), from *swap* to *minix*
  (both mkswap and mkfs.minix being provided by util-linux).
* Replace *dd* commands by *filesize* dedicated module.
* Use FQCNs and name the tasks.
* Update main tests conditionals.

* add a changelog fragment

* Apply suggestions from code review

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

* declare variables as lists when lists are needed

* fix construction without useless conversion

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

tests/integration/targets/filesystem/tasks/overwrite_another_fs.yml

@@ -1,40 +1,55 @@
 ---
 - name: 'Recreate "disk" file'
-  command: 'dd if=/dev/zero of={{ image_file }} bs=1M count={{ fssize }}'
+  community.general.filesize:
+    path: '{{ image_file }}'
+    size: '{{ fssize }}M'
+    force: true
 
-- name: 'Create a swap filesystem'
-  command: 'mkswap {{ dev }}'
+- name: 'Create a minix filesystem'
+  ansible.builtin.command:
+    cmd: 'mkfs.minix {{ dev }}'
 
-- command: 'blkid -c /dev/null -o value -s UUID {{ dev }}'
+- name: 'Get UUID of the new filesystem'
+  ansible.builtin.command:
+    cmd: 'blkid -c /dev/null -o value -s UUID {{ dev }}'
+  changed_when: false
   register: uuid
 
 - name: "Check that an existing filesystem (not handled by this module) isn't overwritten when force isn't used"
-  filesystem:
+  community.general.filesystem:
     dev: '{{ dev }}'
     fstype: '{{ fstype }}'
   register: fs_result
   ignore_errors: True
 
-- command: 'blkid -c /dev/null -o value -s UUID {{ dev }}'
+- name: 'Get UUID of the filesystem'
+  ansible.builtin.command:
+    cmd: 'blkid -c /dev/null -o value -s UUID {{ dev }}'
+  changed_when: false
   register: uuid2
 
-- assert:
+- name: 'Assert that module failed and filesystem UUID is not changed'
+  ansible.builtin.assert:
     that:
       - 'fs_result is failed'
       - 'uuid.stdout == uuid2.stdout'
 
 - name: "Check that an existing filesystem (not handled by this module) is overwritten when force is used"
-  filesystem:
+  community.general.filesystem:
     dev: '{{ dev }}'
     fstype: '{{ fstype }}'
     force: yes
   register: fs_result2
 
-- command: 'blkid -c /dev/null -o value -s UUID {{ dev }}'
+- name: 'Get UUID of the new filesystem'
+  ansible.builtin.command:
+    cmd: 'blkid -c /dev/null -o value -s UUID {{ dev }}'
+  changed_when: false
   register: uuid3
 
-- assert:
+- name: 'Assert that module succeeded and filesystem UUID is changed'
+  ansible.builtin.assert:
     that:
-      - 'fs_result2 is successful'
+      - 'fs_result2 is success'
       - 'fs_result2 is changed'
       - 'uuid2.stdout != uuid3.stdout'