Move models to package `Obsolete`

What is the problem?

• Old models that are actually obsolete but might still be in use by other libraries cannot be deleted.

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

• Move these models to the new top level package Obsolete.
• IBPSA library recently introduced such a package as well.
• Wait for next IBPSA merge into AixLib (see #740 (closed))

The following models with used BaseClasses such as CycleHP will be moved to Obsolete:

• AixLib.Fluid.HeatPumps.HeatPumpDetailed
• AixLib.Fluid.HeatPumps.HeatPumpSimple
• AixLib.Utilities.HeatTransfer.HeatToStar

Further ToDos:

• Use annotation flag for obsolete models