Show vehicle's guns in Factoripedia

[Erythion]

There have been some complaints in the discord about how difficult it is to see how improved a quality vehicle's guns are. The guns are hidden, so the only way to access it is to alt-click on a placed vehicle's inventory.

The property "hidden_in_factoripedia" already exist to accommodate such changes, so changing it to false for vehicle guns would be a nice change.

Another good thing to add would be enabling access to the guns's page from the vehicle's factoripedia page.