Make the project reuse (tool/spec) compliant

[evelikov]

For some context see https://github.com/kmod-project/kmod/pull/151

Tl:Dr:

• For things that are real source files, edited by humans, I prefer the inline identifiers. For everything else (e.g. all the files in testsuite/rootfs-pristine), we should use another approach
• add CI pipeline reuse lint, to ensure newly added files don't regress