Allow image application directory to be configurable

An `applicationDirectory` option on the Maven
`spring-boot:build-image` goal and the Gradle `bootBuildImage` task
can be configured to set the location that will be used to upload
application contents to the builder image, and will contain the
application contents in the generated image.

Closes gh-34786

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/projects/build-image-app-dir/pom.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>org.springframework.boot.maven.it</groupId>
+	<artifactId>build-image-app-dir</artifactId>
+	<version>0.0.1.BUILD-SNAPSHOT</version>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<maven.compiler.source>@java.version@</maven.compiler.source>
+		<maven.compiler.target>@java.version@</maven.compiler.target>
+	</properties>
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>@project.groupId@</groupId>
+				<artifactId>@project.artifactId@</artifactId>
+				<version>@project.version@</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>build-image-no-fork</goal>
+						</goals>
+						<configuration>
+							<image>
+								<builder>projects.registry.vmware.com/springboot/spring-boot-cnb-builder:0.0.2</builder>
+								<applicationDirectory>/application</applicationDirectory>
+							</image>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
+		</plugins>
+	</build>
+</project>

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/projects/build-image-app-dir/src/main/java/org/test/SampleApplication.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2012-2023 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.test;
+
+public class SampleApplication {
+
+	public static void main(String[] args) throws Exception {
+		System.out.println("Launched");
+		synchronized(args) {
+			args.wait(); // Prevent exit"
+		}
+	}
+
+}