Add 'TraceCommandStrings.resx' back to CoreCLR build. TraceCommand cmdlets have been ported in Github.

src/Microsoft.PowerShell.Commands.Utility/project.json

@@ -64,7 +64,6 @@
                         "gen/ImplicitRemotingStrings.cs",
                         "gen/UtilityMshSnapinResources.cs",
                         "gen/OutPrinterDisplayStrings.cs",
-                        "gen/TraceCommandStrings.cs",
                         "gen/UpdateListStrings.cs",
                         "gen/SendMailMessageStrings.cs",
                         "gen/ConvertFromStringResources.cs",
@@ -79,7 +78,6 @@
                         "resources/ImplicitRemotingStrings.resx",
                         "resources/UtilityMshSnapinResources.resx",
                         "resources/OutPrinterDisplayStrings.resx",
-                        "resources/TraceCommandStrings.resx",
                         "resources/UpdateListStrings.resx",
                         "resources/SendMailMessageStrings.resx",
                         "resources/ConvertFromStringResources.resx",