Add support for stateless systems

[evelikov]

As covered in https://0pointer.de/blog/projects/stateless.html.

The Tl:Dr: is we want a) the default config to be in /usr/..., where the sysadmin can either a) override the respectively named files or extend the config file snippets in /etc.

[bluca]

This is only partially fixed, there are still some files shipped in etc

[scaronni]

It got automatically closed when I closed https://github.com/dell/dkms/pull/431. Reopening...