Add artifact merge engines and Kind metadata flow (RFC 018 phase 1)

src/Platform/Microsoft.Testing.Extensions.CtrfReport/CtrfReportGenerator.cs

@@ -24,6 +24,8 @@ public CtrfReportGenerator(IServiceProvider serviceProvider)
 
     protected override string ArtifactDisplayName => ExtensionResources.CtrfReportArtifactDisplayName;
 
+    protected override string? ArtifactKind => "microsoft.testing.ctrf";
+
     protected override string ArtifactDescription => ExtensionResources.CtrfReportArtifactDescription;
 
     protected override string GetGenerationLogMessage(int testResultCount)

src/Platform/Microsoft.Testing.Extensions.CtrfReport/InternalAPI/InternalAPI.Unshipped.txt

@@ -1,4 +1,8 @@
 #nullable enable
+virtual Microsoft.Testing.Extensions.ReportGeneratorBase<TGenerator, TCapturedTestResult>.ArtifactKind.get -> string?
+Microsoft.Testing.Extensions.CtrfReport.CtrfReportMerger
+static Microsoft.Testing.Extensions.CtrfReport.CtrfReportMerger.Merge(System.Collections.Generic.IReadOnlyList<string!>! inputReports) -> string!
+static Microsoft.Testing.Extensions.CtrfReport.CtrfReportMerger.MergeToFileAsync(System.Collections.Generic.IReadOnlyList<string!>! inputPaths, string! outputPath, System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.Task!
 static Microsoft.Testing.Platform.Resources.PlatformResources.NamedPipeDirectoryNotWritableErrorMessage.get -> string!
 static Microsoft.Testing.Platform.Resources.PlatformResources.NamedPipePathTooLongErrorMessage.get -> string!
 static Microsoft.Testing.Platform.Services.ArtifactNamingHelper.ResolveAndSanitize(string! template, string! processName, string! processId, System.DateTimeOffset timestamp, System.Func<string!, string!>! sanitizeLeafFileName) -> string!

src/Platform/Microsoft.Testing.Extensions.HangDump/InternalAPI/InternalAPI.Unshipped.txt

@@ -1,4 +1,5 @@
 #nullable enable
+const Microsoft.Testing.Platform.IPC.FileArtifactMessageFieldsId.Kind = 7 -> ushort
 const Microsoft.Testing.Platform.Helpers.EnvironmentVariableConstants.TESTINGPLATFORM_PIPE_DIRECTORY = "TESTINGPLATFORM_PIPE_DIRECTORY" -> string!
 const Microsoft.Testing.Platform.IPC.NamedPipeServer.MaxUnixDomainSocketPathLengthInBytes = 103 -> int
 static Microsoft.Testing.Platform.IPC.NamedPipeServer.EnsureDirectoryIsWritable(string! directory) -> void

src/Platform/Microsoft.Testing.Extensions.HtmlReport/HtmlReportGenerator.cs

@@ -24,6 +24,8 @@ public HtmlReportGenerator(IServiceProvider serviceProvider)
 
     protected override string ArtifactDisplayName => ExtensionResources.HtmlReportArtifactDisplayName;
 
+    protected override string? ArtifactKind => "microsoft.testing.html";
+
     protected override string ArtifactDescription => ExtensionResources.HtmlReportArtifactDescription;
 
     protected override string GetGenerationLogMessage(int testResultCount)

src/Platform/Microsoft.Testing.Extensions.HtmlReport/InternalAPI/InternalAPI.Unshipped.txt

@@ -1,4 +1,5 @@
 #nullable enable
+virtual Microsoft.Testing.Extensions.ReportGeneratorBase<TGenerator, TCapturedTestResult>.ArtifactKind.get -> string?
 static Microsoft.Testing.Platform.Resources.PlatformResources.NamedPipeDirectoryNotWritableErrorMessage.get -> string!
 static Microsoft.Testing.Platform.Resources.PlatformResources.NamedPipePathTooLongErrorMessage.get -> string!
 static Microsoft.Testing.Platform.Services.ArtifactNamingHelper.ResolveAndSanitize(string! template, string! processName, string! processId, System.DateTimeOffset timestamp, System.Func<string!, string!>! sanitizeLeafFileName) -> string!

src/Platform/Microsoft.Testing.Extensions.JUnitReport/InternalAPI/InternalAPI.Unshipped.txt

@@ -1,4 +1,8 @@
 #nullable enable
+virtual Microsoft.Testing.Extensions.ReportGeneratorBase<TGenerator, TCapturedTestResult>.ArtifactKind.get -> string?
+Microsoft.Testing.Extensions.JUnitReport.JUnitReportMerger
+static Microsoft.Testing.Extensions.JUnitReport.JUnitReportMerger.Merge(System.Collections.Generic.IReadOnlyList<System.Xml.Linq.XDocument!>! inputReports, string! reportName) -> System.Xml.Linq.XDocument!
+static Microsoft.Testing.Extensions.JUnitReport.JUnitReportMerger.MergeToFileAsync(System.Collections.Generic.IReadOnlyList<string!>! inputPaths, string! outputPath, string! reportName, System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.Task!
 static Microsoft.Testing.Platform.Resources.PlatformResources.NamedPipeDirectoryNotWritableErrorMessage.get -> string!
 static Microsoft.Testing.Platform.Resources.PlatformResources.NamedPipePathTooLongErrorMessage.get -> string!
 static Microsoft.Testing.Platform.Services.ArtifactNamingHelper.ResolveAndSanitize(string! template, string! processName, string! processId, System.DateTimeOffset timestamp, System.Func<string!, string!>! sanitizeLeafFileName) -> string!

src/Platform/Microsoft.Testing.Extensions.JUnitReport/JUnitReportGenerator.cs

@@ -33,6 +33,8 @@ public JUnitReportGenerator(IServiceProvider serviceProvider)
 
     protected override string ArtifactDisplayName => ExtensionResources.JUnitReportArtifactDisplayName;
 
+    protected override string? ArtifactKind => "microsoft.testing.junit";
+
     protected override string ArtifactDescription => ExtensionResources.JUnitReportArtifactDescription;
 
     protected override string GetGenerationLogMessage(int testResultCount)