Enable roaming user settings via OneDrive

[shweaver-MSFT]

Fixes #74

PR Type

What kind of change does this PR introduce?

• Feature

What is the current behavior?

Storing data in OneDrive is possible today, but still requires some effort to integrate with the SDK.

What is the new behavior?

I've added a new base implementation of the IRoamingSettingsDataStore called BaseRoamingSettingsDataStore, and built a new OneDriveDataStore on top.

var roamingSettings = RoamingSettingsHelper.CreateForCurrentUser(RoamingDataStore.OneDrive);

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

// TODO:

• Add tests

[ghost]

Thanks shweaver-MSFT for opening a Pull Request! The reviewers will test the PR and highlight if there is any merge conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[shweaver-MSFT]

I haven't had a chance to fulllllllly test this yet, but feel free to start reviewing. Once the WindowsProvider is added, it'll be easier for me to go back and add tests that actually talk to the Graph. The current tests only use the local cache.

[shweaver-MSFT]

Now that the WindowsProvider is checked in, I was able to give it a more thorough test pass and it checks out :)