Add support for globally suppressing CVEs

[kaniini]

Description

There are a lot of CVEs, such as CVE-2023-35116, where we will just want to suppress them across all packages. Presently, we have to do this in every single package we want to NAK the CVE in, but being able to do it in all packages would be helpful.

It might be worth extending the secfixes feed for this.

[luhring]

Interesting idea. Can you expand on the problem scenario a bit? What about the CVE is such that we'd want to NAK it for every package?

[kaniini]

ReDoS type vulnerabilities for one, disputed vulnerabilities like the one I specified above also.