- 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
- Validate the user is assigned to system in authenticated routes where
the user passes in system ID. This protects against a somewhat
impractical scenario where an authenticated user cracks a random 15
character alphanumeric ID of a system that doesn't belong to them via
web API.
- Validate that systemd service exists in database before requesting
service details from agent. This protects against authenticated users
getting unit properties of services that aren't explicitly monitored.
- Refactor responses in authenticated routes to prevent enumeration of
other users' random 15 char system IDs.
