Synchronize display call

- In TerminalUI a display call may be called from
  multiple threads, while only seen to happen on
  windows, should be synchronized.
- Fixes #1039

Author: jvalkeal

spring-shell-core/src/main/java/org/springframework/shell/component/view/TerminalUI.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -257,7 +257,7 @@ public void setNonfullScreenViewRect(BiFunction<Terminal, View, Rectangle> nonfu
 		this.nonfullScreenViewRect = nonfullScreenViewRect;
 	}
 
-	private void display() {
+	private synchronized void display() {
 		log.trace("display() start");
 		size.copy(terminal.getSize());
 		if (fullScreen) {