vdoc: fix handling of .vdocignore files in subdirectories

[ttytm]

Fixes legitimately failing tests in e.g.: #21511, https://github.com/vlang/v/actions/runs/9111620514/job/25049117265?pr=21511

I can't tell why the tests related to this functionality only fail now. I can't reproduce a non-failing state. Moving back several commits and rebuilding with the associated older vc, the tests should have failed earlier.

[spytheman]

It is indeed weird, and the test does pass locally (for me) on both master, and on the PR where it failed, while on the CI and for @Delta456 it failed consistently 🤔 for https://github.com/vlang/v/actions/runs/9117947709/job/25069947585?pr=21515 :

[spytheman]

btw, @Delta456 discovered this:

   > assert mod_list.len == submodules_no_ignore.len, mod_list.str()
     Left value: 10
    Right value: 11
        Message: ['/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/alpha', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/alpha_bravo', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/bravo_charly', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/charly', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/charly/alpha', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/charly/echo', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/charly/foxtrot/golf', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/foxtrot', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/golf', '/tmp/v_1000/tsession_7eebc99e7740_20664589119853/vod_test_module/hotel']

i.e. the charly/delta entry seems to be the missing one, to make .len == 11 as it expected

[ttytm]

Right, there was a .vdocignore containing delta added to the alpha submodule to test .vdocignore files in sub-paths (when the parent already has an .vdocignore file).

On master, the .vdocignore in alpha added delta to the global ignore patterns, so charly/delta was unintentionally ignored.

[ttytm]

For me, the test started to fail locally some time after I did a system update today. Maybe that's the reason. Still weird.

[spytheman]

It may be dependent on the order of the returned entries by os.ls 🤔 .