dockerenv.sh and sudo/root

[My1]

when running make dockerdev, which invokes scripts/dockerenv.sh as root via sudo or otherwise (because docker needs root and using the docker group does not seem to be a recommended option), when not having a running container already (if stopped, it will just ax the current and then create a new one) the command will fail when creating the docker user and group for the reason that at that point both the uid and gid are 0 for root and the created docker already has a root user.

also if calling make dockerdev after such a failure with the user/group creation it will fail again because it couldn't create the docker user it wants to jump into.

fixing this should not be TOO much of an issue:

when running make via sudo 2 extra variables will be created. $SUDO_UID and $SUDO_GID. if these are set one could just take these to replace the $(id -u) and $(id -g), and if docker is run as a pure root, we either need a different solution or ask to at least use it via a normal user through sudo or whatever