[FZ Editor]Add tests to editor #197 + feedback (#29051)

* here are the tests for the fancy zones

* Wrote tests for GridLayoutModel

* Move FancyZonesEditor tests to right place, tests for default layout model

* fixed SettingTheVerticalLayoutShouldBeTheDefault test

* removed coverlet in the test project

* Fixes for comments on pr

* squashed and updated for comments

* Added the test to the pipeline

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Co-authored-by: Drew Gordon <andrewbengordon@gmail.com>
Co-authored-by: Caleb Wightman <agentcboy@gmail.com>

.pipelines/ci/templates/build-powertoys-steps.yml

@@ -197,6 +197,7 @@ steps:
       **\UnitTests-PdfThumbnailProvider.dll
       **\Settings.UI.UnitTests.dll
       **\UnitTests-GcodePreviewHandler.dll
+      **\UnitTests-FancyZonesEditor.dll
       **\UnitTests-PdfPreviewHandler.dll
       **\UnitTests-PreviewHandlerCommon.dll
       **\Microsoft.PowerToys.Run.Plugin.Registry.UnitTests.dll