Add Kahan-Babuška Summation Algorithm and Enhance Variance Indicator Tests

- Introduced a new `Sum` class implementing the Kahan-Babuška algorithm for high-precision rolling summation.
- Added comprehensive documentation for the `Sum` class, detailing its mathematical foundation, performance profile, and use cases.
- Refactored `VarianceIndicator` tests to improve clarity and coverage, including checks for different source types and the ability to change properties.
- Enhanced `UsfIndicator` tests to validate initialization, processing of updates, and property changes.
- Updated `UsfIndicator` implementation to simplify source handling and improve short name generation.
- Modified Qodana configuration to exclude unused auto property accessor warnings.

lib/statistics/variance/Variance.Quantower.cs

@@ -51,6 +51,9 @@ public sealed class VarianceIndicator : Indicator, IWatchlistIndicator
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     protected override void OnUpdate(UpdateArgs args)
     {
+        if (args.Reason != UpdateReason.NewBar && args.Reason != UpdateReason.HistoricalBar)
+            return;
+
         var item = this.HistoricalData[this.Count - 1, SeekOriginHistory.Begin];
         double value = _priceSelector!(item);
         var time = this.HistoricalData.Time();