Analysis hole: attributes on instance methods in RUC types

RUC on type silences warnings from instance methods, but those instance methods may have attributes that should produce warnings. We incorrectly treat RUC on type as suppressing those warnings, even though reflection access to those methods can call the attribute ctor at runtime. Example:

```csharp
class RequiresOnAttributeCtorAttribute : Attribute
{
[RUC("--ATTRIBUTE CTOR--")]
public RequiresOnAttributeCtorAttribute()
{
Console.WriteLine("ATTRIBUTE CTOR CALLED!");
}
}

[RequiresUnreferencedCode("--TypeWithRequires--")]
class TypeWithRequires
{
[RequiresOnAttributeCtor]
public void InstanceMethod() { }
}

public static void Test()
{
foreach (var method in typeof(TypeWithRequires).GetMethods(BindingFlags.Public | BindingFlags.Instance))
{
foreach (var a in method.GetCustomAttributes()) ;
}
}
```