MissingFieldException when assigning to a function pointer field

Trying to use a field with function pointer type throws a MissingFieldException in runtime.

**Repro steps**

Provide the steps required to reproduce the problem:

1. Create a new F# console app
2. Add [TerraFx.Interop.Windows](https://github.com/terrafx/terrafx.interop.windows) package
```xml

```
2. Use the following code:
```fsharp
open TerraFX.Interop.Windows

let mutable windowClassDescriptor = WNDCLASSEXW()
windowClassDescriptor.lpfnWndProc <- 0n // lpfnWndProc is of type delegate* unmanaged in C#

printfn "Successfully Finished"
```

Zip with repro:
[MissingFieldExceptionRepro.zip](https://github.com/dotnet/fsharp/files/7786336/MissingFieldExceptionRepro.zip)

**Expected behavior**

Program finishes and prints "Successfully Finished"

**Actual behavior**

Throws exception
```
Unhandled exception. System.MissingFieldException: Field not found: 'TerraFX.Int
erop.Windows.WNDCLASSEXW.lpfnWndProc'.
at .$Program.main@()

```

**Known workarounds**

No workarounds known to me

**Related information**

Provide any related information (optional):

* Operating system: Win11
* .NET Runtime kind (.NET Core, .NET Framework, Mono): .NET 6, SDK 6.0.100
* Editing Tools (e.g. Visual Studio Version, Visual Studio): Rider (and command line)

[Here is the definition of the field in the TerraFX repo](https://github.com/terrafx/terrafx.interop.windows/blob/main/sources/Interop/Windows/Windows/um/WinUser/WNDCLASSEXW.cs#L19). Commenting out the assignment fixes the problem, but the field is required.