Provide data values in scan results to correspond with license_clarity_score elements

scancode-toolkit now provides a new `license_clarity_score` for example:
```
"license_clarity_score": {
"score": 77,
"has_declared_license_in_key_files": true,
"file_level_license_and_copyright_coverage": 0.1,
"has_consistent_key_and_file_level_licenses": true,
"is_using_only_spdx_licenses": true,
"has_full_text_for_all_licenses": true
},
```
The primary score element in question is ` "has_declared_license_in_key_files"` .
When this element is true, the big question the reader of the scan results will want to ask is what is that `declared_license`? Although scancode returns a list of all the detected licenses in the code that was scanned, I am not aware that it identifies which of those licenses (or license expressions) corresponds to the `declared_license`. It would be tremendoulsy helpful to see that in the scancode results, since it would tell the reader what the primary license (or license expression) of the software code (package) should be. Since scancode has obviously already found that information, in order to set the element to true, it makes sense to present that in the results.

It is possible that the other scoring elements might benefit from a similar improvement, but the `declared_license` seems to be the most important, and would provide the greatest value.