Populate the mod list with mods not installed through the manager

[Systemcluster]

Currently only mods installed through the manager will show up in the mod list. It would be good if all mods would show up in the list.

There are a few issues with this:

• The mod list as tracked by the manager is stored in a separate xml. This list has to be either expanded during launch or a separate run-time only list has to be kept.
• Mods as shown in the manager can consist of multiple mods and dlcs. They would have to be shown as separate entries.
• Additional data like inputs, configs, and xmls may not be inside the installed mod directories. Disabling, enabling or uninstalling untracked mods might not work as expected.

The simplest solution would be to show untracked mods in the list but disabling all functionality (like disabling or uninstalling) for them. There could be an additional column or a different row color indicating this.