Add tests and summary for all implemented standard and track compliance

[agowa]

Component

resolvectl, systemd-networkd, systemd-resolved, tests

Is your feature request related to a problem? Please describe

Provide a list of all implemented standards as well as unit and coverage tests for compliance with each of these standards.

If one wants to know if e.g. systemd-networkd is compliant with RFC6334, just searching the codebase for the RFC number is not enough, as it is listed in https://github.com/systemd/systemd/blob/main/src/systemd/sd-dhcp6-client.h#L44-L189, but does that mean it is fully implemented and supported? Also no unit tests exist that test specifically for compliance with each implemented RFC.

Describe the solution you'd like

1st added CI tests to the project (at least one per standard to get meaningful output of pass/failed tests)
2nd use output of these tests to automatically generate and update a table of supported standards and their status for each (future) release on the systemd website/documentation.

Describe alternatives you've considered

Add a list of all supported standards to the systemd website/documentation and update manually as code changes (bad, as it'd probably get outdated and no automated testing for breaking changes)

The systemd version you checked that didn't have the feature you are asking for

No response