Bugfix: Fix rclone (shimmed by Scoop) and sftp stopped working on Windows

In #3602 a fix was introduced to fix the problem that rclone prematurely exits
when Ctrl+C is pressed on Windows. The solution was to create the subprocess
with its console detached from the restic console. However, such solution
fails when using rclone install by scoop or using sftp with a passphrase-
protected private key. We've fixed that by using a different approach to prevent
Ctrl-C from passing down too early.

https://github.com/restic/restic/issues/3681
https://github.com/restic/restic/issues/3692
https://github.com/restic/restic/pull/3696
