Support for /FU flag broken C++/CLI project

[BartJolling]

Environment

• OS and Version: Windows 11 version 23H2
• VS Code Version: 1.92.2
• C/C++ Extension Version: 1.21.6
• If using SSH remote, specify OS of remote machine:

Bug Summary and Steps to Reproduce

Bug Summary: I'm working on a c++/cli project. The intellisense does not recognize the "Concurrent" namespace. I get red squiggles below Concurrent

Regression of #5819

using namespace System::Collections::Concurrent;

Steps to reproduce:

• Create a c++/cli project
• Add an /FU flag to System.Collections.Concurrent.dll in the c_cpp_properties.json file
• Try to instantiatie a Systems::Collections::Concurrent::Dictionary

The /FU flag is ignored, but I can make it work by including the "System.Collections.Concurrent.dll" directly in the code file. This works:

#using "System.Collections.Concurrent.dll"

using namespace System;
using namespace System::Collections::Concurrent;

Expected behavior: Not needing the workaround to get correct intellisense. The FU flag should not be discarded.

Configuration and Logs

"configurations": [
        {
            "name": "Debug x64 c++/cli",
            "includePath": [
                "${workspaceFolder}/include/"
            ],
            "defines": [
                "_DEBUG",
                "_WINDLL",
                "_UNICODE",
                "UNICODE",
                "BUILD_SHARED_LIB",
                "BUILDING_SHARED_LIB",
                "LIBTIDY_VERSION=\"5.8.0\"",
                "RELEASE_DATE=\"2021.07.10\""
            ],
            "windowsSdkVersion": "10.0.22621.0",
            "compilerPath": "cl.exe",
            "compilerArgs": [
                "/clr:netcore",
                "/AI", "C:/Program Files/dotnet/packs/Microsoft.NETCore.App.Ref/8.0.7/ref/net8.0",
                "/FU", "C:/Program Files/dotnet/packs/Microsoft.NETCore.App.Ref/8.0.7/ref/net8.0/System.Collections.Concurrent.dll"
            ],
            "cStandard": "c17",
            "cppStandard": "c++17",
            "intelliSenseMode": "windows-msvc-x64",
            "browse": {
                "path": [
                    "${workspaceFolder}"
                ],
                "limitSymbolsToIncludedHeaders": true
            },            
            "customConfigurationVariables": {
                "Configuration": "Debug",
                "Platform": "x64",
                "OutDir": "${workspaceFolder}/build/x64/Debug/"
            }
        }
    ],
    "version": 4
}

[ C:\Users\a98017094\Repos\tidy-html5-dotnet\src\Tidy.cpp ]:
    Process ID: 9764
    Memory Usage: 92 MB
    Compiler Path: C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Tools\MSVC\14.40.33807\bin\Hostx64\x64\cl.exe
    Includes:
        C:\Users\a98017094\Repos\tidy-html5-dotnet\include
    System Includes:
        C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Tools\MSVC\14.40.33807\include
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\um
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\ucrt
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\shared
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\winrt
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\cppwinrt
    Defines:
        _DEBUG
        _WINDLL
        _UNICODE
        UNICODE
        BUILD_SHARED_LIB
        BUILDING_SHARED_LIB
        LIBTIDY_VERSION="5.8.0"
        RELEASE_DATE="2021.07.10"
    Standard Version: ms_c++17
    IntelliSense Mode: windows-msvc-x64
    Other Flags:
        --cppcli_netcore
        --no_using_framework_directory
        --cppcli
        --using_directory
        C:/Program Files/dotnet/packs/Microsoft.NETCore.App.Ref/8.0.7/ref/net8.0
Total Memory Usage: 235 MB

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 6988

Other Extensions

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Additional context

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