Tests: enable Swift PM tests in Windows toolchain build

Enable the SwiftPM tests in the Windows toolchain build to get extra
confidence the change did not introduce any regression on the Windows
platform.

Execute SwiftPM tesst in parallel

Fixes: swiftlang/swift-package-manager#8895

utils/build-windows-toolchain.bat

@@ -62,7 +62,7 @@ set TMPDIR=%BuildRoot%\tmp
 set NINJA_STATUS=[%%f/%%t][%%p][%%es] 
 
 :: Build the -Test argument, if any, by subtracting skipped tests
-set TestsList=lld,lldb,lldb-swift,swift,dispatch,foundation,xctest,swift-format,sourcekit-lsp
+set TestsList=lld,lldb,lldb-swift,swift,dispatch,foundation,xctest,swift-format,sourcekit-lsp,swiftpm
 set "TestArg="
 set "Skip=,%SKIP_TESTS%,"
 for %%I in (%TestsList%) do (

utils/build.ps1

@@ -4109,7 +4109,7 @@ function Test-PackageManager() {
   }
 
   Build-SPMProject `
-    -Action Test `
+    -Action TestParallel `
     -Src $SrcDir `
     -Bin "$BinaryCache\$($HostPlatform.Triple)\PackageManagerTests" `
     -Platform $HostPlatform `