Implement wrapper around hostfxr calls

Author: nagilson

src/Installer/Microsoft.Dotnet.Installation/Internal/DotnetArchiveExtractor.cs

@@ -376,11 +376,9 @@ public void Dispose()
         }
     }
 
-    // TODO: InstallerOrchestratorSingleton also checks existing installs via the manifest. Which should we use and where?
-    private IEnumerable<ReleaseVersion> GetExistingSdkVersions(DotnetInstallRoot installRoot)
+    private static IEnumerable<ReleaseVersion> GetExistingSdkVersions(DotnetInstallRoot installRoot)
     {
-        var bundleProvider = new NETBundlesNativeWrapper();
-        NetEnvironmentInfo environmentInfo = bundleProvider.GetDotnetEnvironmentInfo(installRoot.Path);
+        var environmentInfo = HostFxrWrapper.getInfo(installRoot.Path!);
         return environmentInfo.SdkInfo.Select(sdk => sdk.Version);
     }
 }

src/Installer/Microsoft.Dotnet.Installation/Internal/HostFxrWrapper.cs

@@ -0,0 +1,42 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Microsoft.DotNet.NativeWrapper;
+
+namespace Microsoft.Dotnet.Installation.Internal
+{
+    internal class HostFxrWrapper
+    {
+        public static NetEnvironmentInfo getInfo(string installRoot)
+        {
+            var bundleProvider = new NETBundlesNativeWrapper();
+            return bundleProvider.GetDotnetEnvironmentInfo(installRoot); // Could we use get_available_sdks instead to improve perf?
+        }
+
+        public static IEnumerable<DotnetInstall> getInstalls(string installRoot)
+        {
+            var environmentInfo = getInfo(installRoot);
+            var installs = new List<DotnetInstall>();
+            foreach (var sdk in environmentInfo.SdkInfo.ToList())
+            {
+                installs.Add(new DotnetInstall(
+                    new DotnetInstallRoot(installRoot, InstallerUtilities.GetDefaultInstallArchitecture()),
+                    sdk.Version,
+                    InstallComponent.SDK));
+            }
+
+            foreach (var runtime in environmentInfo.RuntimeInfo.ToList())
+            {
+                installs.Add(new DotnetInstall(
+                    new DotnetInstallRoot(installRoot, InstallerUtilities.GetDefaultInstallArchitecture()),
+                    runtime.Version,
+                    InstallComponent.Runtime)); // TODO: Determine the correct InstallComponent based on runtime.Name like release manifest does
+            }
+
+            return installs;
+        }
+    }
+}

src/Installer/dnup/ArchiveInstallationValidator.cs

@@ -75,8 +75,7 @@ private bool ValidateWithHostFxr(string installRoot, ReleaseVersion resolvedVers
     {
         try
         {
-            var bundleProvider = new NETBundlesNativeWrapper();
-            NetEnvironmentInfo environmentInfo = bundleProvider.GetDotnetEnvironmentInfo(installRoot); // Could we use get_available_sdks instead to improve perf?
+            var environmentInfo = HostFxrWrapper.getInfo(installRoot);
 
             if (component == InstallComponent.SDK)
             {