Added Device ID to DeviceInfo

[ryanjkendrick]

Description of Change

Added Device ID to DeviceInfo. Useful for distinguishing between various devices a user owns that your app may be installed on.

API Changes

Added:

• static string DeviceInfo.DeviceId { get; }

PR Checklist

• [x] Has tests (N/A for DeviceInfo)
• [x] Has samples
• [x] Rebased on top of main at time of PR
• [x] Changes adhere to coding standard
• [x] Updated documentation (see walkthrough)

[ghost]

All CLA requirements met.