Add scripts to solution, fix helper script for use from Windows PowerShell, fix attempt to set a null value through COM in Windows PowerShell

Author: JohnMcPMS

src/AppInstallerCLI.sln

@@ -217,6 +217,12 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{02EA681E
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WinGetMCPServer", "WinGetMCPServer\WinGetMCPServer.csproj", "{33745E4A-39E2-676F-7E23-50FB43848D25}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Scripts", "Scripts", "{F49C4C89-447E-4D15-B38B-5A8DCFB134AF}"
+	ProjectSection(SolutionItems) = preProject
+		PowerShell\scripts\Execute-WinGetTests.ps1 = PowerShell\scripts\Execute-WinGetTests.ps1
+		PowerShell\scripts\Initialize-LocalWinGetModules.ps1 = PowerShell\scripts\Initialize-LocalWinGetModules.ps1
+	EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|ARM64 = Debug|ARM64
@@ -1048,6 +1054,7 @@ Global
 		{A0B4F808-B190-41C4-97CB-C8EA1932F84F} = {8D53D749-D51C-46F8-A162-9371AAA6C2E7}
 		{A33223D2-550B-4D99-A53D-488B1F68683E} = {60618CAC-2995-4DF9-9914-45C6FC02C995}
 		{7139ED6E-8FBC-0B61-3E3A-AA2A23CC4D6A} = {02EA681E-C7D8-13C7-8484-4AC65E1B71E8}
+		{F49C4C89-447E-4D15-B38B-5A8DCFB134AF} = {7C218A3E-9BC8-48FF-B91B-BCACD828C0C9}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {B6FDB70C-A751-422C-ACD1-E35419495857}

src/PowerShell/Microsoft.WinGet.Client.Engine/Commands/DownloadCommand.cs

@@ -136,7 +136,10 @@ public void Download(
                             options.Platform = PSEnumHelpers.ToWindowsPlatform(psWindowsPlatform);
                         }
 
-                        options.TargetOSVersion = targetOSVersion;
+                        if (!string.IsNullOrEmpty(targetOSVersion))
+                        {
+                            options.TargetOSVersion = targetOSVersion;
+                        }
 
                         return await this.DownloadPackageAsync(package, options);
                     }));

src/PowerShell/scripts/Initialize-LocalWinGetModules.ps1

@@ -245,6 +245,6 @@ if (-not $SkipImportModule)
     foreach($module in $modules)
     {
         Write-Host "Importing module $($module.Name)" -ForegroundColor Green
-        Import-Module "$moduleRootOutput\$($module.Name)\" -Force
+        Import-Module "$moduleRootOutput\$($module.Name)\$($module.Name).psd1" -Force
     }
 }