[bs-118], [bs-119]: add UI builder features

* MessageSource created automatically (location
spring.messages.basename:messages)
* Thymeleaf configured automatically to look for
templates in classpath:/templates
* Added static resource handlers for classpath:/static
and classpath:/

[Fixes #49832165] [bs-118] Support for thymeleaf templates

spring-bootstrap-samples/spring-bootstrap-trad-sample/src/test/java/org/springframework/bootstrap/sample/trad/TradBootstrapApplicationTests.java

@@ -41,7 +41,7 @@ public class TradBootstrapApplicationTests {
 										.run(TradBootstrapApplication.class);
 							}
 						});
-		context = future.get(10, TimeUnit.SECONDS);
+		context = future.get(30, TimeUnit.SECONDS);
 	}
 
 	@AfterClass