chore: repo cleanup and code quality improvements

- Remove global.json (SDK pinning unnecessary)

- Remove nuget.config, move MyGet source to .csproj RestoreAdditionalProjectSources

- Gitignore ndepend/ entirely, move badges to docs/img/

- Update README.md and docs/ndepend.md badge paths

- Add NDepend project property to QuanTAlib.slnx

- Expand .editorconfig ReSharper/diagnostic suppressions

- Use ArgumentOutOfRangeException instead of ArgumentException

- Use discard _ for unused event sender parameters

- Remove quantalib.code-workspace and sonar-suppressions.json

- Add filter signature SVGs

lib/feeds/csvfeed/CsvFeed.cs

@@ -16,12 +16,12 @@ internal readonly record struct ParsedOhlcv(long Time, double Open, double High,
 [StructLayout(LayoutKind.Auto)]
 internal ref struct OhlcvParseState
 {
-    public long Time;
-    public double Open;
-    public double High;
-    public double Low;
-    public double Close;
-    public double Volume;
+    internal long Time;
+    internal double Open;
+    internal double High;
+    internal double Low;
+    internal double Close;
+    internal double Volume;
 }
 
 /// <summary>