Add ResolvePath tests (#276)

Add required computestorage APIs to allow for running tests of
`ResolvePath`.

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

internal/interop/interop.go

@@ -0,0 +1,25 @@
+//go:build windows
+
+package interop
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+//go:generate go run github.com/Microsoft/go-winio/tools/mkwinsyscall -output zsyscall_windows.go interop.go
+
+//sys coTaskMemFree(buffer unsafe.Pointer) = api_ms_win_core_com_l1_1_0.CoTaskMemFree
+
+func ConvertAndFreeCoTaskMemString(buffer *uint16) string {
+	str := syscall.UTF16ToString((*[1 << 29]uint16)(unsafe.Pointer(buffer))[:])
+	coTaskMemFree(unsafe.Pointer(buffer))
+	return str
+}
+
+func Win32FromHresult(hr uintptr) syscall.Errno {
+	if hr&0x1fff0000 == 0x00070000 {
+		return syscall.Errno(hr & 0xffff)
+	}
+	return syscall.Errno(hr)
+}