addons:open command does not work with sudo on windows

[KevinBrolly]

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

Currently upon running addons:open using sudo the following error is displayed:

ENOENT: no such file or directory, open 'C:\tmp\heroku-sso.html'

What is the expected behavior?

It is expected that the file would be found and the browser window successfully opens the selected addon.

I believe the reason for this issue is that the ssoPath defined here - https://github.com/heroku/cli/blob/master/packages/addons-v5/commands/addons/open.js#L12

'/tmp/heroku-sso.html' is not a valid path for temporary files in a windows system. The issue happens when we try to open this file and find it has not been created - https://github.com/heroku/cli/blob/master/packages/addons-v5/commands/addons/open.js#L61

We may benefit from using the os.tmpdir() node function to ensure that at the file is stored in a valid location on all supported platforms.