Fix remote shell to support custom banners

Update the remote shell to use the `Banner` interface when possible.

Fixes gh-3988
Closes gh-5453

spring-boot-starters/spring-boot-starter-remote-shell/src/main/resources/commands/crash/login.groovy

@@ -1,8 +1,25 @@
 welcome = { ->
-	if (!crash.context.attributes['spring.environment'].getProperty("spring.main.show_banner", Boolean.class, Boolean.TRUE)) {
+
+	def environment = crash.context.attributes['spring.environment']
+	def propertyResolver = new org.springframework.boot.bind.RelaxedPropertyResolver(environment, "spring.main.");
+	def beanFactory = crash.context.attributes['spring.beanfactory']
+
+	if (!propertyResolver.getProperty("show-banner", Boolean.class, Boolean.TRUE)) {
 		return ""
 	}
 
+	// Try to print using the banner interface
+	if (beanFactory != null) {
+		try {
+			def banner = beanFactory.getBean("springBootBanner")
+			def out = new java.io.ByteArrayOutputStream()
+			banner.printBanner(environment, null, new java.io.PrintStream(out))
+			return out.toString()
+		} catch (Exception ex) {
+			// Ignore
+		}
+	}
+
 	// Resolve hostname
 	def hostName;
 	try {