build: update build rules for CustomAction removal

With #63887, the swift compiler can dynamically inject the VFS overlay
paths to add the modulemaps and apinotes for the Windows SDK.  This
obviates the need for the custom action in the SDK installation.  Update
the build rules to account for this along with
swiftlang/swift-installer-scripts#176.

Author: compnerd

utils/build-windows-toolchain.bat

@@ -933,15 +933,13 @@ msbuild %SourceRoot%\swift-installer-scripts\platforms\Windows\toolchain.wixproj
 :: signtool sign /f Apple_CodeSign.pfx /p Apple_CodeSign_Password /tr http://timestamp.digicert.com /fd sha256 %PackageRoot%\toolchain\toolchain.msi
 
 :: Package sdk.msi
-msbuild %SourceRoot%\swift-installer-scripts\platforms\Windows\CustomActions\SwiftInstaller\SwiftInstaller.vcxproj -t:restore
 msbuild %SourceRoot%\swift-installer-scripts\platforms\Windows\sdk.wixproj ^
   -p:RunWixToolsOutOfProc=true ^
   -p:OutputPath=%PackageRoot%\sdk\ ^
   -p:IntermediateOutputPath=%PackageRoot%\sdk\ ^
   -p:PLATFORM_ROOT=%PlatformRoot%\ ^
   -p:SDK_ROOT=%SDKInstallRoot%\ ^
-  -p:SWIFT_SOURCE_DIR=%SourceRoot%\swift\ ^
-  -p:PlatformToolset=v142
+  -p:SWIFT_SOURCE_DIR=%SourceRoot%\swift\
 :: TODO(compnerd) actually perform the code-signing
 :: signtool sign /f Apple_CodeSign.pfx /p Apple_CodeSign_Password /tr http://timestamp.digicert.com /fd sha256 %PackageRoot%\sdk\sdk.msi