Enable https://github.com/cashapp/licensee

[jingtang10]

Describe the Issue
Enable the plugin and configure it so it allows only compatible licences in our dependencies.

Would you like to work on the issue?
@kevinmost made a headstart :)

[Tarun-Bhardwaj]

@kevinmost , could you please provide an ETA for fixing this issue?

[kevinmost]

This change is ready to go, but we are not submitting it until we verify that we can remove a problematic dependency from HAPI FHIR, rather than exempting that dependency in our licensee config.

[jingtang10]

With hapifhir/hapi-fhir#3043 merged. I believe we should be able to remove the exception for saxon-he after hapi's next release.