support fuzzy search in neovim menus

[teto]

Is your feature request related to a problem? Please describe. I would like to fuzzy search menu entries. It's possible with fzf-lua via :FzlLua menus, here is the implementation: https://github.com/ibhagwan/fzf-lua/blob/57402a41ac6f983640c41af43ce0c37929e61c43/lua/fzf-lua/providers/nvim.lua#L418

I wonder if that would make for a good builtins ? or is the new policy to create new extensions (in which case extension autodiscovery would be nice)