[FW][ADD] rpc: Go examples

Examples rely on `kolo/xmlrpc` as well as on the standard library package `log` to panic on error, matching snippets in other languages (which tend to raise exceptions).

As with other languages, only the RPC interaction is spelled out.

closes #5128

Forward-port-of: #5064
Signed-off-by: Xavier Morel (xmo) <[email protected]>

Author: mrhdias