detect: per tx detect flags to a u8 progress value

detect: per tx detect flags to a u8 progress value

Reduce per tx space for tracking detection/prefilter progress. Instead
of a per direction u64 of flags, where each bit reflected a progress
value, use a simple u8 to track the linear progression through the
progress values. Use an offset to allow 0 to mean no value.

Add flags field as well to track "skip detect" and "inspect complete".