sudo-rs does not set the terminal foreground process group

[pvdrz]

Describe the bug
sudo-rs does not set the command as the foreground process for the pty follower.

To Reproduce
Steps to reproduce the behavior:

1. Compile sudo-rs and use any sudoers file that lets you execute commands as any user.
2. Run any long-running command with sudo, like yes
3. Check ps aux | grep yes and notice that the monitor is the foreground process instead of the actual command (i.e. the monitor has a + sign in the STAT column and the command does not).

Expected behavior
The command should be the foreground process for the pty.

Environment (please complete the following information):

• Linux distribution: Arch Linux (btw) with kernel 6.3.3
• sudo-rs commit hash: e13cab0

Additional context
This might be the reason why ^Z is ignored by sudo-rs at the moment. Still need to investigate. So it might be related to #245 and #325

cc @squell