Created MathCore module, a module meant to regroup all math utils that are not generic enough that they should be in Core (in order not to bloat it) or owned by the foundation team :

* Moved directed graph utils from audio to core, in namespace UE::MathCore::Graph
* Renamed Depth/BreadthFirstTraversal to Depth/BreadthFirstNodeTraversal and added Depth/BreadthFirstEdgeTraversal to traverse the graph edges
* Added FindLeaves method to retrieve graph nodes with no children from a starting node

Created MathCoreTests low-level test executable :
* Moved directed graph unit tests there
* Enabled on CIS on all platforms

#tests low-level tests
#rb chris.constantinescu, danny.couture, phil.popp, johan.torp

[CL 31680629 by jonathan bard in ue5-main branch]

Engine/Source/Programs/LowLevelTests/MathCoreTests/MathCoreTests.Build.cs

@@ -0,0 +1,48 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+using UnrealBuildTool;
+
+public class MathCoreTests : TestModuleRules
+{
+	protected Metadata MathCoreTestsMetadata = new Metadata() {
+		TestName = "MathCore",
+		TestShortName = "MathCore",
+		ReportType = "xml",
+		SupportedPlatforms = {
+			UnrealTargetPlatform.Win64,
+			UnrealTargetPlatform.Linux,
+			UnrealTargetPlatform.Mac,
+			UnrealTargetPlatform.Android,
+			UnrealTargetPlatform.IOS } };
+
+	/// <summary>
+	/// Test metadata to be used with BuildGraph
+	/// </summary>
+	public Metadata TestMetadata
+	{ 
+		get { return MathCoreTestsMetadata; }
+	}
+
+	public MathCoreTests(ReadOnlyTargetRules Target) : base(Target, InUsesCatch2:true)
+	{
+		PrivateDependencyModuleNames.AddRange(
+			new string[] {
+				"Core",
+				"MathCore",
+			});
+
+		string PlatformCompilationArgs;
+		foreach (var Platform in UnrealTargetPlatform.GetValidPlatforms())
+		{
+			if (Platform == UnrealTargetPlatform.Android)
+			{
+				PlatformCompilationArgs = "-allmodules -architectures=arm64";
+			}
+			else
+			{
+				PlatformCompilationArgs = "-allmodules";
+			}
+			TestMetadata.PlatformCompilationExtraArgs.Add(Platform, PlatformCompilationArgs);
+		}
+		UpdateBuildGraphPropertiesFile(TestMetadata);
+	}
+}

Engine/Source/Programs/LowLevelTests/MathCoreTests/MathCoreTests.Target.cs

@@ -0,0 +1,15 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+using UnrealBuildTool;
+
+[SupportedPlatforms(UnrealPlatformClass.All)]
+public class MathCoreTestsTarget : TestTargetRules
+{
+	public MathCoreTestsTarget(TargetInfo Target) : base(Target)
+	{
+		// Collects all tests decorated with #if WITH_LOW_LEVELTESTS from dependencies
+		// TODO [jonathan.bard] : disabled for now : we can enable this (and move the tests in MathCoreTests to a Tests sub-folder alongside the code they're validating), when https://jira.it.epicgames.com/browse/UE-205189 is implemented : 
+		//  Without this, the tests from all linked modules (i.e. Core) would be run as part of this executable, which would be wasteful : 
+		// bWithLowLevelTestsOverride = true;
+	}
+}