[SHELL32][SHELL32_APITEST][SDK] Implement SHGetUserDisplayName (#7612)

Implemementing missing features...
JIRA issue: CORE-19278
- Add netapi32 and secur32 delay importing.
- Move function definition from stubs.cpp into utils.cpp.
- Include some security headers in utils.cpp.
- Adapt <secext.h> to C++.
- Add prototype to <undocshell.h>.

modules/rostests/apitests/shell32/CMakeLists.txt

@@ -41,6 +41,7 @@ list(APPEND SOURCE
     ShellInfo.cpp
     ShellState.cpp
     SHGetAttributesFromDataObject.cpp
+    SHGetUserDisplayName.cpp
     SHLimitInputEdit.cpp
     menu.cpp
     shelltest.cpp)

modules/rostests/apitests/shell32/SHGetUserDisplayName.cpp

@@ -0,0 +1,30 @@
+/*
+ * PROJECT:     ReactOS API tests
+ * LICENSE:     GPL-2.0+ (https://spdx.org/licenses/GPL-2.0+)
+ * PURPOSE:     Test for SHGetUserDisplayName
+ * COPYRIGHT:   Copyright 2025 Katayama Hirofumi MZ (katayama.hirofumi.mz@gmail.com)
+ */
+
+#include "shelltest.h"
+#include <undocshell.h>
+
+START_TEST(SHGetUserDisplayName)
+{
+    HRESULT hr;
+    WCHAR szBuf[MAX_PATH];
+    ULONG cchBuf;
+
+    hr = SHGetUserDisplayName(NULL, NULL);
+    ok_hex(hr, E_INVALIDARG);
+
+    hr = SHGetUserDisplayName(szBuf, NULL);
+    ok_hex(hr, E_INVALIDARG);
+
+    cchBuf = _countof(szBuf);
+    hr = SHGetUserDisplayName(NULL, &cchBuf);
+    ok_hex(hr, E_INVALIDARG);
+
+    cchBuf = _countof(szBuf);
+    hr = SHGetUserDisplayName(szBuf, &cchBuf);
+    ok_hex(hr, S_OK);
+}

modules/rostests/apitests/shell32/testlist.c

@@ -42,6 +42,7 @@ extern void func_ShellHook(void);
 extern void func_ShellState(void);
 extern void func_SHGetAttributesFromDataObject(void);
 extern void func_SHGetFileInfo(void);
+extern void func_SHGetUserDisplayName(void);
 extern void func_SHLimitInputEdit(void);
 extern void func_SHParseDisplayName(void);
 extern void func_SHSimpleIDListFromPath(void);
@@ -88,6 +89,7 @@ const struct test winetest_testlist[] =
     { "ShellState", func_ShellState },
     { "SHGetAttributesFromDataObject", func_SHGetAttributesFromDataObject },
     { "SHGetFileInfo", func_SHGetFileInfo },
+    { "SHGetUserDisplayName", func_SHGetUserDisplayName },
     { "SHLimitInputEdit", func_SHLimitInputEdit },
     { "SHParseDisplayName", func_SHParseDisplayName },
     { "SHSimpleIDListFromPath", func_SHSimpleIDListFromPath },