Improvement: Always apply namespace regex

[peinjoh]

SSVC provides https://github.com/CERTCC/SSVC/blob/main/src/ssvc/utils/ssvc_namespace_pattern.abnf

The ABNF gets generated into a regex, which gets included into the namespace FromString impl generated by our typegen.
Namespace validation runs on strings, so there is no guarantee that his always happens (as it does during selection list validation)

We could hard-couple the namespace validation to the generated Namespace type, ensuring that any validated namespaces as been both a) regex validated and b) semantically validated

[peinjoh]

TODO: Check if reverse domain notation is validated through the regex via unit test