Track cursor position when writing prompt

We were running into a situation where we'd print the prompt on the same
line that we had previously printed it. This was especially noticable
when stepping through the debugger.

This change ensures that we always write a new line if that situation
occurs.

Author: SeeminglyScience

src/PowerShellEditorServices/Services/PowerShell/Host/PsesInternalHost.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation.
+// Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
 using System;
@@ -77,6 +77,8 @@ internal class PsesInternalHost : PSHost, IHostSupportsInteractiveSession, IRuns
 
         private bool _resettingRunspace;
 
+        private (int x, int y)? _lastPromptPosition;
+
         public PsesInternalHost(
             ILoggerFactory loggerFactory,
             ILanguageServerFacade languageServer,
@@ -757,7 +759,20 @@ private void DoOneRepl(CancellationToken cancellationToken)
             try
             {
                 string prompt = GetPrompt(cancellationToken);
+
+                // Check cursor position to see if we're in the exact same spot as the last time we
+                // wrote the prompt. If we are, write a new line.
+                if (_lastPromptPosition is not null)
+                {
+                    (int x, int y) current = (System.Console.CursorLeft, System.Console.CursorTop);
+                    if (current == _lastPromptPosition.Value)
+                    {
+                        UI.WriteLine();
+                    }
+                }
+
                 UI.Write(prompt);
+                _lastPromptPosition = (System.Console.CursorLeft, System.Console.CursorTop);
                 string userInput = InvokeReadLine(cancellationToken);
 
                 // If the user input was empty it's because: