Add support denite#util#open in wsl

[virusbb001]

Problems summary

denite#util#open is not supported in WSL

Expected

Open URL in default browser of Windows Host.

Environment Information (Required!)

• denite version (SHA1): 4e7eec5

• OS: Ubuntu 20.04.3 LTS in Windows 10 (WSL)

• Vim/neovim version:

  • vim: 8.2.1-3575
  • nvim: v0.5.1

• :checkhealth or :CheckHealth result(neovim only):

Provide a minimal init.vim with less than 50 lines (Required!)

" Your minimal init.vim
set runtimepath+=~/path/to/denite.nvim/

Solution

Try to open the same way of Windows when running in WSL and cmd.exe is available