add reuse copyright/license compliance

[kbroch-rivosinc]

https://reuse.software/

tasks:

• update all files with reuse header (copyright and license are the same, just slight formatting changes)
• add pre-commit hook to check compliance
• add github workflow to check compliance
• add badge for reuse compliance

This PR can be uses as a template: rivosinc/pcie-power-logger#2