Change the mapping of discrete switching states in FiniteB6BridgeConverter

[XyDrKRulof]

Currently the FiniteB6BridgeConverter uses the following switching state to voltage mapping:

|0|lower|lower|lower|
|1|lower|lower|upper|
|2|lower|upper|lower|
|3|lower|upper|upper|
|4|upper|lower|lower|
|5|upper|lower|upper|
|6|upper|upper|lower|
|7|upper|upper|upper|

This is a logical mapping counting upwards. We want this to be changed into a mapping which resembles the movement through the voltage hexagon:

|0|lower|lower|lower|
|1|upper|lower|lower|
|2|upper|upper|lower|
|3|lower|upper|lower|
|4|lower|upper|upper|
|5|lower|lower|upper|
|6|upper|lower|upper|
|7|upper|upper|upper|

In order to allow older trained agents to work on this new scheme, a wrapper has to be implemented which maps the new switching states to the old ones.