Package Licenses do not work correctly with embedded license

[dansiegel]

Description

When a custom license is used or a license file is explicitly provided by the NuGet Author, rather than having a blank URL for the package license we get back a deprecation Url from the NuGet Sdk.

This should instead detect when the deprecation Url is provided and provide a link back to the API where we can retrieve the embedded license and return it. This would be an endpoint that allows anonymous requests which should be fine from a security standpoint because we are only exposing the License not the actual package.