[idd] helper: open the IDD log directory

The interactive Helper now writes its own log under LocalAppData so it
can run with the desktop user token. The tray menu should still take
users to the system-wide IDD and service logs under ProgramData.

Expose the log-directory resolver and have Open log directory request
the ProgramData location explicitly. Keep Helper log storage unchanged.

idd/LGCommon/CDebug.h

@@ -22,6 +22,7 @@
 
 #include <Windows.h>
 #include <fstream>
+#include <string>
 
 class CDebug
 {
@@ -51,7 +52,8 @@ class CDebug
       LEVEL_MAX
     };
 
-    const wchar_t *logDir() { return m_logDir.c_str(); }
+    const wchar_t *logDir() const { return m_logDir.c_str(); }
+    static std::wstring GetLogDir(Location location);
     void Init(const wchar_t * name,
       Location location = Location::ProgramData);
     void Log_va(CDebug::Level level, const char *function, int line, const wchar_t *fmt, va_list args);