Service locations on Windows (Pre-logon, Always-on)

[t-aleksander]

Adds support for service locations (hidden VPN locations that are connected before user logs in).

The location configurations are stored in the ProgramData folder with appropriate ACLs.

The connection is established either when:

1. When the service starts and the system is in pre-logon stage or the location is in always on mode
2. When the location mode changes (when the administrator changes it) during config polling. The update makes the location reset and turn on/off according to their mode and current system stage (e.g. when switching from always on to pre-logon the location should disconnect if the user is logged in).

Related issue: #1636