Use Santa preferences to determine machine ID

[1dustindavis]

The Rudolph cli assumes that it can determine the local machineID from a Santa machine mapping plist at a specific path, but Santa supports a few different methods for defining the machineID. Ideally, Rudolph would determine the machine ID using the same methods as Santa.

Retrieving for Error: failed to get machineID: could not open santa machine mapping plist: open /Library/Preferences/com.google.santa.machine-mapping.plist: no such file or directory