The knowledgebase was just added in the simulator case, not in the
device. That meant that the tcp error was not reported.
Also added another possible case of tcp errors to be picked up and be
shown as a known error (device throws a diff error when on airplane
mode).
fixes: https://github.com/xamarin/xamarin-macios/issues/8659
* [Harness] Small refactor to get the knowledge base out of jenkins.
Some small changes to make things a little easier to understand:
* Add a new method in case we find known install issues.
* enable nullable, lets go step by step.
* Move logic outside Jenkins.cs
* Add tests! \o/