sysutils/screen: Add session creation time when list active sessions

Reimplement Debian patches to display screen session creation time and
sort the list of sessions by date.

Output example for 'screen -ls' command

There is a screen on:

14059.pts-7.1302amd64-head      (08/15/23 10:02:52)     (Attached)

1 Socket in /tmp/screens/S-root.

Reviewed by: cy
Differential Revision: https://reviews.freebsd.org/D41469