fix(hub): System.HasUser - return true if SHARE_ALL_SYSTEMS=true (#1891)

- move hub's GetEnv function to new utils package to more easily share
across different hub packages
- change System.HasUser to take core.Record instead of user ID string
- add tests

agent/utils/utils.go

@@ -1,3 +1,4 @@
+// Package utils provides utility functions for the agent.
 package utils
 
 import (