[SHELL32] shlexec: Initial support of App Paths (#4850)

- Fix SHELL_TryAppPathW helper function by using SHRegQueryValueExW function.
- Fix SHRegQueryValueExA/W functions.
CORE-11335

sdk/include/reactos/undocshell.h

@@ -721,6 +721,26 @@ IStream* WINAPI SHGetViewStream(LPCITEMIDLIST, DWORD, LPCTSTR, LPCTSTR, LPCTSTR)
 
 EXTERN_C HRESULT WINAPI SHCreateSessionKey(REGSAM samDesired, PHKEY phKey);
 
+LONG WINAPI SHRegQueryValueExA(
+    HKEY hkey,
+    LPCSTR lpValueName,
+    LPDWORD lpReserved,
+    LPDWORD lpType,
+    LPBYTE lpData,
+    LPDWORD lpcbData);
+LONG WINAPI SHRegQueryValueExW(
+    HKEY hkey,
+    LPCWSTR pszValue,
+    LPDWORD pdwReserved,
+    LPDWORD pdwType,
+    LPVOID pvData,
+    LPDWORD pcbData);
+#ifdef UNICODE
+    #define SHRegQueryValueEx SHRegQueryValueExW
+#else
+    #define SHRegQueryValueEx SHRegQueryValueExA
+#endif
+
 /*****************************************************************************
  * INVALID_FILETITLE_CHARACTERS
  */