[Feature]: Better handling for "on-hold" packages

What is the installation method of your PatchMon server?

setup.sh native install script

What is the version of your PatchMon server?

2.0.2

Briefly describe the feature

Patchman should be able to handle "on-hold" packages

Detailed description

Currently, packages that are "on-hold" are invisible to Patchmon.
It should be possible to set a package on hold and to see the packages that are on hold.

Why is this useful?

Sometimes, packages have to be kept back, but it is dangerous to exclude them from every view.