Fix Service object leak on emulation stop

Services created with the ServiceFramework base class install themselves as HleHandlers with an owning shared_ptr in the ServerPort ServiceFrameworkBase::port member variable, creating a cyclic ownership between ServiceFrameworkBase and the ServerPort, preventing deletion of the service objects.

Fix that by removing the ServiceFrameworkBase::port member because that was only used to detect multiple attempts at installing a port. Instead store a flag if the port was already installed to achieve the same functionality.