Suricata

Add a new configuration option to filter payload extraction in EVE JSON alerts based on the rule's classtype.

Currently, when payload: yes is enabled in the alert output, payloads are extracted for all alerts. In some environments we want payloads to be extracted only for specific rules (and we use `classtypes` for that).

I envision adding an optional payload-only-classtypes configuration parameter under the alert output type that accepts a list of classtype names.

When configured:
- Payloads are only extracted for alerts whose classtype matches one in the list
- If the list is empty or not configured, the default behavior is preserved (payloads extracted for all alerts when payload: yes)