(cherry picked from commit 7e330f533f414947aeba00fbacb091c1757d8b2b)

adding integration testcases for multiple batteries, adapting hybrid strategy to take over state of battery system to testpowertrain, write information for all batteries to .vmod, batterysystem: fix writing .vmod SoC of whole system

saving and loading battery system works, write modal results for batterysystem (total/average of all batteries / battery strings)

update electric motor form to use two voltage levels, adapt input data, json reader, json writer for electric motor, adapt testcases to make it compile

This reverts commit fbf8bc83.

(cherry picked from commit 2b724382)