Since many implementations use the ReleasePacket callback to issue
their verdict, no thread ctx is available. To work around this
just register the stats in a `thread_local` variable instead.

ReleasePacket based verdicts can happen in several threads,
depending on the runmode details.

Only register and update if in IPS mode.

This adds support to all capture methods for these counters.

Ticket: OISF#4756.

{
  "accepted": 296185,
  "blocked": 162,
  "rejected": 0,
  "replaced": 0,
  "drop_reason": {
    "decode_error": 0,
    "defrag_error": 0,
    "defrag_memcap": 0,
    "flow_memcap": 0,
    "flow_drop": 94,
    "applayer_error": 0,
    "applayer_memcap": 0,
    "rules": 3,
    "threshold_detection_filter": 0,
    "stream_error": 63,
    "stream_memcap": 0,
    "stream_midstream": 2,
    "nfq_error": 0,
    "tunnel_packet_drop": 0
  }
}

Ticket: OISF#6230.