Restructure the `PolynomialCompressor` classes

[fwitte]

Resolve #825

The PolynomialCompressor classes have some special touch to them, as

• they require a precalculation step and
• you pass some parameters through a dictionary to the component (the reference_state)

This leads to the fact, that the reference_state specific parameters come in a specific unit, which cannot be deviated from. Breaking up the reference state into its single elements and using those will be an extra step, as the reference_state dictionary is also passed to the precalculation method. It should be discussed with the of the (power) users of this component, what is the most reasonable API.