runtime(vim): Update base-syntax, improve :menu{,translate} highlighting (vim/vim#14162)
Improve :menu and :menutranslate highlighting.
- Match args to :menutranslation and :popup.
- Only highlight special notation in {rhs} of :menu, like :map.
- Allow line continuations in {rhs} of :menu and between {english} and
{mylang} of :menutranslation, matching common usage.
- Bug fixes.
62b26040eb
Co-authored-by: dkearns <dougkearns@gmail.com>
84b6ae82c7
