feat(Diagnostic): Address rule CA1822

src/Avalonia.Diagnostics/Diagnostics/Screenshots/FilePickerHandler.cs

@@ -47,7 +47,7 @@ namespace Avalonia.Diagnostics.Screenshots
         /// </summary>
         public string Title { get; } = "Save Screenshot to ...";
 
-        Window GetWindow(IControl control)
+        static Window GetWindow(IControl control)
         {
             var window = control.VisualRoot as Window;
             var app = Application.Current;
@@ -61,7 +61,7 @@ namespace Avalonia.Diagnostics.Screenshots
         protected async override Task<Stream?> GetStream(IControl control)
         {
             Stream? output = default;
-            var result = await GetWindow(control).StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions
+            var result = await FilePickerHandler.GetWindow(control).StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions
             {
                 SuggestedStartLocation = new BclStorageFolder(new DirectoryInfo(ScreenshotsRoot)),
                 Title = Title,

src/Avalonia.Diagnostics/Diagnostics/ViewModels/ControlDetailsViewModel.cs

@@ -83,7 +83,7 @@ namespace Avalonia.Diagnostics.ViewModels
                             {
                                 var setterValue = regularSetter.Value;
 
-                                var resourceInfo = GetResourceInfo(setterValue);
+                                var resourceInfo = ControlDetailsViewModel.GetResourceInfo(setterValue);
 
                                 SetterViewModel setterVm;
 
@@ -122,7 +122,7 @@ namespace Avalonia.Diagnostics.ViewModels
 
         public bool CanNavigateToParentProperty => _selectedEntitiesStack.Count >= 1;
 
-        private (object resourceKey, bool isDynamic)? GetResourceInfo(object? value)
+        private static (object resourceKey, bool isDynamic)? GetResourceInfo(object? value)
         {
             if (value is StaticResourceExtension staticResource)
             {