vim-patch:8.2.0898: missing help for a function goes unnoticed

Problem:    Missing help for a function goes unnoticed.
Solution:   Add a test. (Gary Johnson)

https://github.com/vim/vim/commit/6b0e528368415476bfc3a8414c9c70f9852b1517

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Test relies on parsing runtime/doc/*.txt and src/evalfunc.c .
Error-prone because Vim and Nvim diverged on both documentation
and source code in spite of ported Vim patches.
Importing src/nvim/eval.lua is an alternative
but it uses associatve index such that it's unsorted.

Treat it as N/A because I can't rewrite any of its tests
under minimal effort.

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Co-authored-by: Bram Moolenaar <Bram@vim.org>

scripts/vim_na_files.txt

@@ -98,6 +98,7 @@ src/testdir/test_crypt.vim
 src/testdir/test_cscope.vim
 src/testdir/test_glvs.vim
 src/testdir/test_hardcopy.vim
+src/testdir/test_function_lists.vim
 src/testdir/test_job_fails.vim
 src/testdir/test_json.vim
 src/testdir/test_listener.vim