mod(engine): Fix and describe MINGW64 build
This commit closes the gap for MINGW64 builds.
Note that the Windows build heavily relies on changes of the openscenario_api library (see https://github.com/RA-Consulting-GmbH/openscenario.api.test/pull/156), why it's currently an experimental feature.
Yet, the changes won't have any impact on existing stuff (see readme)