Free parameter input/output for stepper - part 1

This MR considers the propagation of free parameters in the propgation. This is meant to be analogue to the propagation of SingleBoundParameters and SingleCurvilinearParameters but without any conversion between global and local coordinates. In this first of two parts, the EDM for the free(global) coordainates is implemented and tested. The construction follows thereby the construction of surface related parametrisations but simplifies the construction by the demand of 8 dimensional parametrisations. Since this MR will break up the inheritance relation between all the different classes that consider parametrisation, it became necessary to treat the correct implementation in terms of API by adding a concept (ParameterConcept). The parametrisations are mostly passed as templated parameters which are only used by the Propagator. The test whether a class fulfills the corresponding concept is therefore performed inside the propagation methods itself.

The second MR related to #635 (closed) will consider the actual implementation of the this EDM into the stepper classes

Closes #635 (closed)