Add nested dependency's licenses in omnibus package

Summary

In omnibus we provide a copy of the licenses files from our dependencies in the /opt/gitlab/LICENSES folder of every gitlab install.

We have these for each of components that we build here in omnibus, as well as some scripting that ensures we fetch the licenses used in the ruby gems as well.

However, from #4939 (closed) we see that we are missing includes licences from nested golang and npm dependencies.

Proposal

From: #4939 (comment 299084496)

I could update our license_finder report to output the license text, and notice text. (These are two report columns that are available in the tool) And we could get rid of the current gem license generator, and instead update the omnibus licensing to create the appropriate license files from the reports while generating the dependencies_json

Note that in order to do this we would first need to update our license finder gem: gitlab-org/distribution/team-tasks#453 (closed)