Green: Use project references to avoid reference conversion issue

The previous issue was that copying metadata references directly between compilations wasn't working for `CompilationReference`s.
Originally I thought it was only possible to reference a compilation of the same type, and hence copying references wouldn't work, but now I suspect it just needs an accompanying project reference

Author: GrahamTheCoder

ICSharpCode.CodeConverter/Shared/ProjectConversion.cs

@@ -72,7 +72,7 @@ public static IEnumerable<ConversionResult> ConvertProjectContents(Project proje
             var solutionFilePath = project.Solution.FilePath;
             var solutionDir = Path.GetDirectoryName(solutionFilePath);
             var compilation = project.GetCompilationAsync().GetAwaiter().GetResult();
-            var projectConversion = new ProjectConversion(compilation, solutionDir, languageConversion, GetConvertedCompilation(project.GetCompilationAsync().GetAwaiter().GetResult(), languageConversion));
+            var projectConversion = new ProjectConversion(compilation, solutionDir, languageConversion, GetConvertedCompilationWithProjectReferences(project, languageConversion));
             foreach (var conversionResult in ConvertProjectContents(projectConversion)) yield return conversionResult;
         }