Rework generic starting value generator and convergence checks

[fwitte]

Currently, generating the starting values mostly works with water due to the way the project grew. However, they should depend on the functionality of the component as well as the fluid (maybe even the label?), i.e.

• compressor: inlet and outlet state both gaseous
• turbine: inlet and outlet state both gaseous
• pump: inlet and outlet state both liquid
• condenser:
  • inlet state hot side: saturated gas
  • outlet state hot side: saturated liquid
  • inlet/outlet state cold side: both liquid or gaseous
• desuperheater:
  • inlet state hot side: gaseous
  • outlet state hot side: saturated gas
  • other side: both liquid or gaseous
• heat exchanger: ???
• solar collector and parabolic trough: liquid at inlet and outlet
• ... to complete this list...

Similar checks can be carried out for the convergence_check functions of these components.