Feature Request: add `LicenseName` field to the output

[mmaetzler]

I want to start with saying: I love this software! Thanks for creating it!

I was wondering if there is an easy way to add the license name as a field to the output? The output files right now have a license file with the raw text of the license, but I was wondering if you would be open to add the licenseName, in the form of an SPDX license identifier to the output as well?

Background: In our software attributions list, we list all the included components, their name, version and license identifier. Then, when one clicks on a license, the full text appears, but we first want to start by showing just the license identifier.

In our use case we are using the json output of the package list.