Minor improvements on DPMS classes:

- Refactored DevicePolicyData.dump() on its own method.
- Fixed broken javadoc links on BaseIDevicePolicyManager
- Changed DevicePolicyData's userHandle to userId

Test: adb shell dumpsys device_policy
Bug: 172691310

Change-Id: Ia29ffb8a07a92663f5d46b0feca1b2f3c590f7f4