Cross-check functionality in sv-tests against slang's "Language Support" page

[mithro]

@MikePopoloski has created an awesome "Language Support" page for slang @ https://sv-lang.com/language-support.html.

It would be good it someone could go through that page and check how it compares to the coverage that sv-tests has. Maybe it might inspire some extra grouping or tagging that we should be doing.