Replace old heat pump model in example GeothermalHeatPumpBase

What is the problem?

The example Fluid.Examples.GeothermalHeatPump.BaseClasses.GeothermalHeatPumpBase uses the obsolete model AixLib.Obsolete.Year2019.Fluid.HeatPumps.HeatPumpSimple. The example seems to be actually not a bad one, showing some kind of complex example including a rudimentary heat pump control. Thus, I would avoid deleting the example.

How do we want to solve it? Describe the solution you'd like

• Decide for important outputs and add simulate-and-plot script
• Change class of heat pump to one of the existing heat pump classes
• Preserve simulation results of outputs of interest as much as possible. Since so far no baseline exists, receiving different results due to class exchange is okay.
• Add reference results