Allow passing --details to zypper dup

[JohnVeness]

When doing "tumbleweed update" and there is a new snapshot to install, this script will do a "zypper dup" to show the packages that will be installed. Before using tumbleweed-cli I usually did "zypper dup --details". I tried doing "tumbleweed update --details", hoping it would pass that onto "zypper dup", but it said "unknown option --details". Could you add this function, maybe?

Similarly, I can see that it might sometimes be helpful to pass through "--download-only".