"sudo" missing from Docker container

The file Docker file `bazel/oci/Dockerfile` creates the `ubuntu` user like this:

```
RUN useradd --system --create-home --home-dir=/home/ubuntu --shell=/bin/bash --gid=root --groups=sudo --uid=1000 ubuntu
```

The intention seems to be that this user can use `sudo`. Unfortunately the `sudo` package itself is missing which makes it difficult to install extra packages when using this container.