Refactor tests and improve random number generation handling; update Dema, Ema, Sma, Tema, Wma, and GBM classes for consistency and clarity

lib/averages/sma/Sma.Tests.cs

@@ -1,5 +1,6 @@
 namespace QuanTAlib.Tests;
 
+#pragma warning disable S2245 // Random is acceptable for simulation/testing purposes
 public class SmaTests
 {
     [Fact]
@@ -422,9 +423,9 @@ public class SmaTests
     {
         double[] source = new double[10000];
         double[] output = new double[10000];
-        var rng = new Random(42);
+        var rng = new Random(42); // nosemgrep
         for (int i = 0; i < source.Length; i++)
-            source[i] = rng.NextDouble() * 100;
+            source[i] = rng.NextDouble() * 100; // nosemgrep
 
         // Warm up
         Sma.Calculate(source.AsSpan(), output.AsSpan(), 100);