Suricata

If we look at https://app.codecov.io/gh/OISF/suricata/blob/master/src/detect-tls.c
we will notice that some keywords, such as 'subject' (https://suricata.readthedocs.io/en/latest/rules/tls-keywords.html#tls-subject) and 'issuerdn' (https://suricata.readthedocs.io/en/latest/rules/tls-keywords.html#tls-issuerdn) are not covered by our tests.

This ticket's work includes:
- Identify other tls keywords that also need coverage
- Add suricata-verify tests with rules that make use of those
- Check if we need to update our userguide documentation on those rules, and improve it accordingly