Project rule assemblies cannot reference engine rule assemblies

Steps to Reproduce
Create a file called MyInsights.Target.cs in any game project Source directory with the following content, and run GenerateProjectFiles.bat:

`using UnrealBuildTool;
using EpicGames.Core;

[SupportedPlatforms(“Win64”, “Linux”, “Mac”)]
public class MyInsightsTarget : UnrealInsightsTarget
{
public MyInsightsTarget(TargetInfo Target) : base(Target)
{
}
}`