Cleaning up reqnroll generated files

[acostmig]

I found myself adding this to my csproj in order to have them be deleted on clean.

This might be a good replacement for codebehind file addition to the csproj

<Target Name="RemoveFeatureFilesOnClean" AfterTargets="Clean">
  <Delete Files="@(ReqnrollGeneratedCode)" />
</Target>
<ItemGroup>
  <ReqnrollGeneratedCode Include="$(ProjectDir)\**\*.feature.cs" />
</ItemGroup>

[gasparnagy]

I like this idea. Could you please make a PR for this? Probably should go somewhere here: https://github.com/reqnroll/Reqnroll/blob/main/Reqnroll.Tools.MsBuild.Generation/build/Reqnroll.Tools.MsBuild.Generation.targets

[304NotModified]

Nice improvement!