WiX: Remove PackageModelSyntax component

`PackageModelSyntax` module is about to get removed from Swift
Package Manager because the functionality has been moved to
swift-syntax. Sourcekit-LSP was the only external user of the
library which is no longer the case.

Author: xedin

platforms/Windows/cli/cli.wxi

@@ -698,9 +698,6 @@
       <Component>
         <File Source="$(ToolchainRoot)\usr\bin\PackageModel.dll" />
       </Component>
-      <Component>
-        <File Source="$(ToolchainRoot)\usr\bin\PackageModelSyntax.dll" />
-      </Component>
       <Component>
         <File Source="$(ToolchainRoot)\usr\bin\SourceControl.dll" />
       </Component>