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.

obj/project.packagespec.json

@@ -0,0 +1 @@
+"restore":{"projectUniqueName":"C:\\Users\\simulateur\\Desktop\\GsaViewer\\GsaViewer.csproj","projectName":"GsaViewer","projectPath":"C:\\Users\\simulateur\\Desktop\\GsaViewer\\GsaViewer.csproj","outputPath":"C:\\Users\\simulateur\\Desktop\\GsaViewer\\obj\\","projectStyle":"PackageReference","originalTargetFrameworks":["net9.0"],"sources":{"https://api.nuget.org/v3/index.json":{}},"frameworks":{"net9.0":{"targetAlias":"net9.0","projectReferences":{}}},"warningProperties":{"warnAsError":["NU1605"]},"restoreAuditProperties":{"enableAudit":"true","auditLevel":"low","auditMode":"direct"},"SdkAnalysisLevel":"9.0.300"}"frameworks":{"net9.0":{"targetAlias":"net9.0","dependencies":{"Avalonia":{"target":"Package","version":"[11.3.6, )"},"Avalonia.Desktop":{"target":"Package","version":"[11.3.6, )"},"Avalonia.Diagnostics":{"target":"Package","version":"[11.3.6, )"},"Avalonia.Fonts.Inter":{"target":"Package","version":"[11.3.6, )"},"Avalonia.Themes.Fluent":{"target":"Package","version":"[11.3.6, )"},"CommunityToolkit.Mvvm":{"target":"Package","version":"[8.2.1, )"}},"imports":["net461","net462","net47","net471","net472","net48","net481"],"assetTargetFallback":true,"warn":true,"frameworkReferences":{"Microsoft.NETCore.App":{"privateAssets":"all"}},"runtimeIdentifierGraphPath":"C:\\Program Files\\dotnet\\sdk\\9.0.306/PortableRuntimeIdentifierGraph.json"}}