Update fixtures to current ansible-core docs; improve linting of array stubs

[felixfontein]

This includes semantic markup for most plugin docs.

Once ansible/ansible#81450 is merged and we can use that some of the unrelated information will vanish. (I'm really looking forward to that...)

[felixfontein]

I had to add a code change since one of the current tests was now failing: RV(ansible.builtin.stat#module:stat[foo.bar].exists) is now correct, since the type of the ansible.builtin.stat module's return value stat changed from complex to dict - and dictionaries allow subscription with [].

This shows another problem: while stat is a dictionary, stat[something] can be correct (depending on what exactly something is), while stat[something].exists is not correct (or at least not linkable to a documented return value). So I added a new rule to only allow array stubs for dictionaries if they show up as the last element (i.e. foo.bar[baz] is ok, but foo[bar].baz is not if foo is a dictionary).

[felixfontein]

I'll merge in a couple of days if nobody objects by then.

[gotmax23]

Side note:

IMO, this code would be a easier to understand if

antsibull-docs/src/antsibull_docs/lint_plugin_docs.py

Line 379 in cbb2c03

for index, part in enumerate(name):

was written along the lines of

    for index, (part, array_stub) in enumerate(name):
        ...

Accessing the tuples returned by split_option_like_name() without unpacking them is a bit confusing, as the reader has to go look at that function's signature to figure out that it's a 2 tuple and what those two values refer to.

[felixfontein]

Good point. I'll have to clean that up at some point.

[felixfontein]

@gotmax23 thanks a lot for reviewing this!