Rename package to make it clear that this is Go

- I hate the convention of putting "go" on every library wrapper, but
   unfortunately the utility is undeniable.  I don't want people to find
   this repo when they are actually looking for the "real" onnxruntime
   repo.

onnxruntime_test.go

@@ -1,4 +1,4 @@
-package onnxruntime
+package onnxruntime_go
 
 import (
 	"encoding/json"