Add kernel version to depmod command line.

Download and extract the Linux Kernel's Debian package.
Generate module dependencies.

To avoid json-in-json-in-json the metadata is directly put in a file and
the values do not need to be quoted anymore.
The current configuration features only json-in-json.

Add a kernel version in dracut command-line options.

This script allows to by-pass shacache/shadir: execute ```40upload-image.sh```
instead of ```35install-image-directly.sh```.