Add project restore files and NuGet cache for GsaViewer

- Created project.nuget.cache to store NuGet package cache information.
- Added project.packagespec.json to define project restore settings and dependencies.
- Included rider.project.restore.info for Rider IDE integration.

GsaEditor/obj/Debug/net8.0/GsaEditor.GeneratedMSBuildEditorConfig.editorconfig

@@ -0,0 +1,28 @@
+is_global = true
+build_property.AvaloniaNameGeneratorIsEnabled = true
+build_property.AvaloniaNameGeneratorBehavior = InitializeComponent
+build_property.AvaloniaNameGeneratorDefaultFieldModifier = internal
+build_property.AvaloniaNameGeneratorFilterByPath = *
+build_property.AvaloniaNameGeneratorFilterByNamespace = *
+build_property.AvaloniaNameGeneratorViewFileNamingStrategy = NamespaceAndClassName
+build_property.AvaloniaNameGeneratorAttachDevTools = true
+build_property.TargetFramework = net8.0
+build_property.TargetPlatformMinVersion = 
+build_property.UsingMicrosoftNETSdkWeb = 
+build_property.ProjectTypeGuids = 
+build_property.InvariantGlobalization = 
+build_property.PlatformNeutralAssembly = 
+build_property.EnforceExtendedAnalyzerRules = 
+build_property._SupportedPlatformList = Linux,macOS,Windows
+build_property.RootNamespace = GsaEditor
+build_property.ProjectDir = C:\Users\simulateur\Desktop\GsaViewer\GsaEditor\
+build_property.EnableComHosting = 
+build_property.EnableGeneratedComInterfaceComImportInterop = 
+build_property.EffectiveAnalysisLevelStyle = 8.0
+build_property.EnableCodeStyleSeverity = 
+
+[C:/Users/simulateur/Desktop/GsaViewer/GsaEditor/App.axaml]
+build_metadata.AdditionalFiles.SourceItemGroup = AvaloniaXaml
+
+[C:/Users/simulateur/Desktop/GsaViewer/GsaEditor/Views/MainWindow.axaml]
+build_metadata.AdditionalFiles.SourceItemGroup = AvaloniaXaml