Add CosmosDB components and gocosmos SQL driver

[mihaitodor]

This is a revamp of #1583, where I did the initial exploration to add these components. Since then, gocosmos became an official Microsoft SQL driver for CosmosDB and it is currently marked as experimental, so I decided to include it as well because it comes with some extra goodies, such as support for hierarchical partition keys and cross-partition queries, which are not currently supported by the azcosmos driver.