tools/esptool: cleanup preflash and qemu integration
tools/esptool: cleanup preflash and qemu integration

OlegHahm/RIOT,ant9000/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OTAkeys/RIOT,kaspar030/RIOT,miri64/RIOT,OTAkeys/RIOT,authmillenon/RIOT,jasonatran/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,ant9000/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,jasonatran/RIOT,ant9000/RIOT,ant9000/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,OTAkeys/RIOT,miri64/RIOT,jasonatran/RIOT,ant9000/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,OlegHahm/RIOT,miri64/RIOT,authmillenon/RIOT,kYc0o/RIOT,OlegHahm/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,kaspar030/RIOT,miri64/RIOT,miri64/RIOT,kYc0o/RIOT,jasonatran/RIOT