Unstrip `ldtoken` for fields

[ds5678]

As far as I know, this instruction is only used for array initializers that have constant data. I wrote a helper method:

public static Il2CppSystem.RuntimeFieldHandle ManagedFieldToIl2CppField(System.RuntimeMethodHandle handle)
{
    var methodInfo = System.Reflection.MethodInfo.GetMethodFromHandle(handle)!;
    var fieldInfoField = Il2CppInteropUtils.GetIl2CppFieldInfoPointerFieldForGeneratedFieldAccessor(methodInfo)!;
    var fieldInfoPtr = (nint)fieldInfoField.GetValue(null)!;
    var fieldInfo = (Il2CppSystem.Reflection.FieldInfo)Il2CppObjectPool.Get(fieldInfoPtr)!; // Not sure if this is how it works
    return fieldInfo.FieldHandle;
}

The unstripped code would be:

• Use ldtoken on the get method of the field accessor property. There is no C# equivalent to this, but the runtime should handle it fine.
• Call the helper method.

However, this would require either:

• Support for constant field data in type injection
• Refusing to translate ldtoken for unstripped fields