Add transcritical versions of exisiting subcritical heat pumps

[jfreissmann]

Description of task

The model data base already has a lot of subcritical heat pump processes. The task in this issue is to create more transcritical versions of the existing heat pump models. This mainly concers changing the condenser to a normal heat exchanger and setting the heat output pressure.

Necessary steps

• Create copy of existing heat pump model class
• Change the setup to allow a transcritical process
• Create corresponding input parameter file
• Create topologie flow sheet as .svg file for light and dark mode
• Add the class to the hp_models dictionairy of variables.py

[jfreissmann]

Issue resolved with PR #17