Add artifact coordinates for all azure-core-http implementations

[srnagar]

The doc is great, but It could be much better if it had all artifact names listed in "Replace the default HTTP client" section.

The text claims there is an http client implementation using JDK's HttpClient, but it seems that the artifact is missing (at least on Maven Central). Googling for JdkAsyncHttpClientBuilder referred in text gives a couple of links to javadocs, but https://search.maven.org/ can't find any artifact containing this class.

Thanks!

Originally reported here - https://github.com/MicrosoftDocs/azure-dev-docs/issues/713