Preserve PowerShell's CommandCompletion result sort order in VS Code

This change causes VS Code to preserve PowerShell's original
CommandCompletion result sort order by creating SortText entries for every
completion result, not just parameters.

Resolves PowerShell/vscode-powershell#579.

Author: daviwil

src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

@@ -1506,17 +1506,12 @@ private static CompletionItem CreateCompletionItem(
                 }
             }
 
-            // We want a special "sort order" for parameters that is not lexicographical.
-            // Fortunately, PowerShell returns parameters in the preferred sort order by
-            // default (with common params at the end). We just need to make sure the default
-            // order also be the lexicographical order which we do by prefixig the ListItemText
-            // with a leading 0's four digit index.  This would not sort correctly for a list
-            // > 999 parameters but surely we won't have so many items in the "parameter name"
-            // completion list. Technically we don't need the ListItemText at all but it may come
-            // in handy during debug.
-            var sortText = (completionDetails.CompletionType == CompletionType.ParameterName)
-                ? $"{sortIndex:D3}{completionDetails.ListItemText}"
-                : null;
+            // Force the client to maintain the sort order in which the
+            // original completion results were returned. We just need to
+            // make sure the default order also be the lexicographical order
+            // which we do by prefixing the ListItemText with a leading 0's
+            // four digit index.
+            var sortText = $"{sortIndex:D4}{completionDetails.ListItemText}";
 
             return new CompletionItem
             {