Support for Unity's Cloud Content Delivery CDN

Unity have their own CDN for release management and content delivery. Perhaps Rider can list buckets and show content, possibly uploading/downloading?

See [the blog post](https://blogs.unity3d.com/2020/09/10/enterprise-gaming-cdn-get-started-in-an-hour-with-unitys-cloud-content-delivery) and [home page](https://unity.com/products/cloud-content-delivery).

Start with the linked Unity Cloud Content Delivery blog post and home page to understand the service and its API. Then inspect the existing Rider and Unity integration entry points, if present, and clarify whether the intended scope is listing buckets, viewing content, uploading, downloading, or all of these. Done criteria require an agreed feature scope and supported operations.

Written by the indexing model from the issue text.