CHG insert commit hashes into builds

Since the images are always built through the makefile, we can do it with the [GIT_TAG](https://github.com/AnubisLMS/IDE/blob/main/Makefile#L3) environment variable. We can pass it to the build containers through a build arg.

We can maybe save the commit as a file to `/etc/anubis/COMMIT` or something. Maybe add it as an environment variable `ANUBIS_IDE_COMMIT` or something.