Use lowercase name for package folders (#2162)

.NET CLI build 3546 started placing packages in:

    ~/.nuget/packages/microsoft.codeanalysis.common

instead of:

    ~/.nuget/packages/Microsoft.CodeAnalysis.Common

Where the previous (capitalized) version corresponded directly to the
package's name. Now they are all lower-cased.

src/TypeCatalogParser/Main.cs

@@ -34,7 +34,7 @@ namespace TypeCatalogParser
                                          // Get the real reference assemblies
                                          from y in x.CompileTimeAssemblies where y.Path.EndsWith(".dll")
                                          // Construct the path to the assemblies
-                                         select $"{context.PackagesDirectory}/{x.Name}/{x.Version}/{y.Path};");
+                                         select $"{context.PackagesDirectory}/{x.Name.ToLower()}/{x.Version}/{y.Path};");
 
             Console.WriteLine($"List of reference assemblies written to {outputPath}");
         }