Add ArmDesktopSdk.props and a Directory.Build.props to force-import ARM desktop SDK settings (WindowsSDKDesktopARMSupport and centralized handling of the ARM desktop preprocessor define). Remove x64-specific configurations, property sheets and duplicated ARM preprocessor definitions from multiple .vcxproj files to simplify supported platforms. Update pkgread to use package-based pugixml library paths and set TreatWChar_tAsBuiltInType, and tweak solution configuration entries in AppInstallerReset.sln.
