Add Keyboard Navigation To Color Picker (#9144)

<!-- Enter a brief description/summary of your PR here. What does it fix/what does it change/how was it tested (even manually, if necessary)? -->
## Summary of the Pull Request

Add the keyboard navigation to the color picker.
Test manually.

<!-- Other than the issue solved, is this relevant to any other issues/existing PRs? -->
## References

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist
* [x] Closes #6675
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: #xxx
* [ ] Schema updated.
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

<!-- Provide a more detailed description of the PR, other things fixed or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

Tested manually

(cherry picked from commit ca226d6)

src/cascadia/TerminalApp/ColorPickupFlyout.xaml

@@ -12,7 +12,7 @@
         </Style>
     </Flyout.FlyoutPresenterStyle>
     <StackPanel Orientation="Horizontal">
-        <StackPanel>
+        <StackPanel XYFocusKeyboardNavigation="Enabled">
             <VariableSizedWrapGrid Orientation="Horizontal" MaximumRowsOrColumns="4" HorizontalAlignment="Center" Margin="0, 3, 0, 0">
                 <VariableSizedWrapGrid.Resources>
                     <Style TargetType="Rectangle">