detect: use explicit rule types

detect: use explicit rule types

Instead of using flags to indicate a rule type, use an explicit `type`
field.

This will make it more clean in code paths what paths a rule is taking,
and will allow easier debugging as well as analyzer output.

Define the following fields:

- SIG_TYPE_IPONLY: sig meets IP-only criteria and is handled by the IP-only
  engine.
- SIG_TYPE_PDONLY: sig inspects protocol detection results only.
- SIG_TYPE_DEONLY: sig inspects decoder events only.
- SIG_TYPE_PKT:    sig is inspected per packet.
- SIG_TYPE_PKT_STREAM: sig is inspected against either packet payload or
  stream payload.
- SIG_TYPE_STREAM: sig is inspected against the reassembled stream
- SIG_TYPE_APPLAYER: sig is inspected against an app-layer property, but not
  against a tx engine.
- SIG_TYPE_APP_TX: sig is inspected the tx aware inspection engine(s).

Ticket: #6085.