[PR #9133/a789bd12 backport][stable-10] Add the accumulate filter (#9220)

Add the accumulate filter (#9133)

* Add the accumulate filter

- Add myself as a maintainer for it.
- Some integration tests.

* accumulate: fix documentation and add test aliases

The aliases file was copied over from
tests/integrations/targets/filter_dict/aliases as the documentation[1]
suggests to use the same group as existing similar tests.

[1]: https://docs.ansible.com/ansible/latest/dev_guide/testing/sanity/integration-aliases.html

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

* accumulate: documentation: markup consistency with other plugins

Suggested-by: Felix Fontein <felix@fontein.de>
Suggested-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

* filter/accumulate: Validate input is a Sequence

Accepting arbitrary iterables might lead to surprising behavior so we
are stricter on what we accept in the filter.
Relaxing those requirements is easier than retrofitting them, in terms
of backwards compatibility.

Suggested-by: Felix Fontein <felix@fontein.de>
Signed-off-by: Max Gautier <mg@max.gautier.name>

* filter/accumulate: Document the behavior with a string

Signed-off-by: Max Gautier <mg@max.gautier.name>

---------

Signed-off-by: Max Gautier <mg@max.gautier.name>
(cherry picked from commit a789bd128f)

Co-authored-by: Max Gautier <mg@max.gautier.name>

.github/BOTMETA.yml

@@ -135,6 +135,8 @@ files:
   $doc_fragments/xenserver.py:
     labels: xenserver
     maintainers: bvitnik
+  $filters/accumulate.py:
+    maintainers: VannTen
   $filters/counter.py:
     maintainers: keilr
   $filters/crc32.py: