Allow setting managing organization for the device

The Profile Owner of a managed profile can set a string that will be
shown in the UI to identify the organization managing the profile.
This CL extends the functionality to the Device Owner of a managed
device.

Bug: 32692748
Test: DevicePolicyManagerTest unit test + CTS test in separate CL

Change-Id: I47295da2fd6485ebf0e890da13990a044accaf17