Add two drafts for humid air handling

[fwitte]

This implements two different possibilities of handling the HAPropsSI interface of CoolProp.

1. A HumidAirConnection with the humidity ratio w as additional variable and handling the fluid property calls on the connection instance. While it is nice, that the humidity ratio is explicitly exposed the main problem is, that the fluid property calls which do not go through a Connection instance (e.g. calling T_mix_ph from inside a component like the MovingBoundaryHeatExchanger) need to be handled separately and not really in a nice way.
2. A new mixing_rule "humidair" that calls HAPropsSI by calculating the humidity ratio w from the given fluid mass fractions in the fluid vector of a connection. With this the user has to calculate the mass fraction dictionary for the fluid specification before specifying it to the connection, but that could also be done through a method I think. So I do much prefer this solution.

Given, that 2 is the preferred solution, there are two relevant changes:

• https://github.com/CHPApS/tespy/blob/cd17f164ac9f3020d99f5311c95a3638f8a98498/src/tespy/tools/fluid_properties/mixtures.py
• https://github.com/CHPApS/tespy/blob/cd17f164ac9f3020d99f5311c95a3638f8a98498/src/tespy/tools/fluid_properties/functions.py

An example is available in https://github.com/CHPApS/tespy/blob/cd17f164ac9f3020d99f5311c95a3638f8a98498/tests/test_tools/test_fluid_properties/humidair.ipynb