Check for Separate Security and Privacy sections

[xfq]

Describe the solution you'd like

The W3C horizontal review guidelines mentions separate Security Considerations and Privacy Considerations sections:

Before requesting privacy and security reviews from the Privacy Interest Group (PING) and security reviewers, respectively, authors must write both "Security Considerations" and "Privacy Considerations" sections for their documents,
https://w3ctag.github.io/security-questionnaire/#reviews

Maybe it's useful to check it in ReSpec and emit a warning for REC-track documents using the w3c profile.

Additional context

There's a similar issue in Bikeshed: speced/bikeshed#2120

[marcoscaceres]

Hmm... agreeing with what Tab said over in BS... but yeah, we can modify the checker. That should be pretty easy.

[marcoscaceres]

@xfq, initial PR for this:
https://github.com/w3c/respec/pull/3922/files

If you'd like to take a look... I might make it complain also for "ED" status and might be more explicit on exactly which "rec track" documents need this.