Close junegunn#1018

Run the command as is in cmd.exe with no parsing and escaping.
Explicity set cmd.SysProcAttr so execCommand does not escape the command.
Technically, the command should be escaped with ^ for special characters, including ".
This allows cmd.exe commands to be chained together.

See neovim/neovim#7343 (comment)

However, this requires a new shellescape function that is specific to one of the following:
- interactive prompt
- batchfile
- command name
fzf#shellescape in the Vim plugin can handle only the batchfile.

quoteEntry uses strconv.Quote in Windows but this escapes more than \ and "
Use strings.Replace to handle only \ and ".
    - double all backslashes
    - double-quote the entry, escaping all inner double quotes with backslash