[SHELL32] CGuidItemContextMenu: Fix pwszCLSID leak (#6607)

Fix memory leak.
JIRA issue: CORE-19478
- Use CoTaskMemFree for pwszCLSID to avoid memory leak
  in CGuidItemContextMenu_CreateInstance function.

dll/win32/shell32/folders/CRegFolder.cpp

@@ -116,6 +116,7 @@ HRESULT CGuidItemContextMenu_CreateInstance(PCIDLIST_ABSOLUTE pidlFolder,
         {
             wcscpy(&key[6], pwszCLSID);
             AddClassKeyToArray(key, hKeys, &cKeys);
+            CoTaskMemFree(pwszCLSID);
         }
     }
     AddClassKeyToArray(L"Folder", hKeys, &cKeys);