Golang: Change HTTP ClientRequest type to DataFlow::CallNode

[jason-invision]

Could the type of ClientRequest be changed to a DataFlow::CallNode?

In the javascript version of CodeQL the type is an InvokeNode, which allows for

      exists(ClientRequest req | sink = req.getAnArgument())

In the golang version, I had to do

    exists(HTTP::ClientRequest request, DataFlow::CallNode call | request = call and sink = call.getAnArgument())

[max-schaefer]

I'm not sure. I think keeping the more general type has its advantage, just in case we end up wanting to model an API where the client request isn't actually a call. Note that you can use postfix casts to suppress most of the syntactic noise:

exists(HTTP::ClientRequest req | sink = req.(DataFlow::CallNode).getAnArgument())

Longer term, I think it would be worth considering introducing a member predicate on HTTP::ClientRequest that does what you are using getAnArgument() for here, though I'm not entirely sure what that is.