Rework of FlinkMiniCluster

Over the time, the FlinkMiniCluster has become quite complex to support all different execution modes (batch vs. streaming, standalone vs. ha with ZooKeeper, single ActorSystem vs. multiple ActorSystems, etc.). There is no consistent way of configuring all these options. Therefore it would be good to rework the FlinkMiniCluster to avoid configuring it via the Configuration object and instead to use explicit options which can be turned on and off.