VSMEF018 Suppress CS0649 for MEF imported fields on exported parts

VSMEF018 suppresses CS0649 for imported fields on exported MEF parts.

Why this matters

MEF assigns imported fields during composition, not in the constructor or initializer that the C# compiler analyzes. That can make valid imports look like permanently unassigned fields and produce CS0649 incorrectly.

When it applies

The suppressor applies to fields on exported parts when the field is decorated with either flavor of Import-style attribute that this library recognizes.

MEFv2 does not support field imports, so in practice field suppression only applies to MEFv1 field imports.

Example

using System;
using System.ComponentModel.Composition;

[Export]
public class SomeService
{
    [Import(AllowDefault = true)]
    private Lazy<IDependency>? dependency;
}

public interface IDependency { }