In cases where the generated files depend on changes to Nvim itself,
generating the files with an older version of Nvim will fail because
those changes are not present in the older version.

For example, if a new option is added then the generator script should
be run with the version of Nvim that contains the new option, or else
the generation will fail.

Co-authored-by: dundargoc <gocdundar@gmail.com>

runtime(doc): documentation updates

This is a collection of various improvements to the help pages

closes vim/vim#12790

https://github.com/vim/vim/commit/596ad66d1ddb742ef349e98eb06b8e4052f68f51

Co-authored-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Houl <anwoku@yahoo.de>
Co-authored-by: Doug Kearns <dougkearns@gmail.com>
Co-authored-by: Adri Verhoef <a3@a3.xs4all.nl>

Also make gen_eval_files.lua render vimdoc helpExamples properly if the line
begins with the `>` marker.

Problem: sidescrolloff and scrolloff options work slightly
         different than other global-local options
Solution: Make it behave consistent for all global-local options

It was noticed, that sidescrolloff and scrolloff options behave
differently in comparison to other global-local window options like
'listchars'

So make those two behave like other global-local options. Also add some
extra documentation for a few special local-window options.

Add a few tests to make sure all global-local window options behave
similar

closes: vim/vim#12956
closes: vim/vim#12643

https://github.com/vim/vim/commit/4a8eb6e7a9df10f79bf95301ced012f0d6a13088

Co-authored-by: Christian Brabandt <cb@256bit.org>

This is needed to give recent LuaLS the right idea about optional fields.

refactor(api): use typed keysets