Graph controls don't support XY Focus

## Describe the bug
The LoginButton and PeoplePicker Graph controls don't work at all when using XY navigation.

- [ ] Is this bug a regression in the toolkit? If so, what toolkit version did you last see it work:

## Steps to Reproduce
Steps to reproduce the behavior:
1. [Create blank app](https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/development-environment-setup#create-your-first-app)
1. [Add Graph controls](https://github.com/windows-toolkit/Graph-Controls#-getting-started)
1. [Disable mouse mode](https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/how-to-disable-mouse-mode)
1. [Run on an Xbox One console](https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/development-environment-setup#create-your-first-app)
1. Attempt to use the controls with a gamepad

## Expected behavior
The controls should be functional.

## Screenshots
If applicable, add screenshots to help explain your problem.

## Environment

```
NuGet Package(s):

Package Version(s):

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [X] May 2019 Update (18362)
- [ ] Insider Build (build number: )

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [X] May 2019 Update (18362)
- [ ] Insider Build (xxxxx)

Device form factor:
- [ ] Desktop
- [X] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio
- [ ] 2017 (version: )
- [X] 2019 (version: )
- [ ] 2019 Preview (version: )

```

## Additional context
Add any other context about the problem here.

Commencez par suivre les étapes de reproduction indiquées dans une application vierge sur une Xbox One avec le mode souris désactivé, puis examinez les contrôles Graph LoginButton et PeoplePicker. C’est terminé lorsque les deux contrôles fonctionnent avec une navigation XY basée sur une manette de jeu dans l’environnement Windows 10 indiqué.

Rédigé par le modèle d'indexation à partir du texte de l'issue.