Report separately unknown licenses and related non-conclusive license detections

## Short Description

Several rules are used to detect license reported as "unknown","unknown-license-reference", etc. are mixed with bona fide conclusive license detection rules that point to concrete licenses.
We should split these and deal with them and report them separately (See also #1675 )
The benefit would be clearer separation of actionable license detection results vs. detections that would need some review.

## Select Category

- [x] Enhancement
- [ ] Add License/Copyright
- [x] Scan Feature
- [ ] Packaging
- [ ] Documentation
- [ ] Expand Support
- [ ] Other