Support java.nio.file Paths and FileSystems with nested jars

Add a `NestedFileSystemProvider` implementation so that the JDK's
`ZipFileSystem` can load content from nested jars and nested
directory entries.

Creating a `ZipFileSystem` may be a relatively expensive operation as
zip structures need to be parsed and in the case of directory entries
a virtual datablock nees to be generated on the fly. As such, we
install the `ZipFileSystem` as late as possible since in a typical
application it may never be needed.

This commit also tweaks Gradle and Maven plugins to ensure that the
service loader file is written to repackaged jars.

Closes gh-7161

spring-boot-tests/spring-boot-integration-tests/spring-boot-loader-tests/src/intTest/java/org/springframework/boot/loader/LoaderIntegrationTests.java

@@ -51,11 +51,12 @@ class LoaderIntegrationTests {
 
 	@ParameterizedTest
 	@MethodSource("javaRuntimes")
-	void readUrlsWithoutWarning(JavaRuntime javaRuntime) {
+	void runJar(JavaRuntime javaRuntime) {
 		try (GenericContainer<?> container = createContainer(javaRuntime, "spring-boot-loader-tests-app", null)) {
 			container.start();
 			System.out.println(this.output.toUtf8String());
 			assertThat(this.output.toUtf8String()).contains(">>>>> 287649 BYTES from")
+				.contains(">>>>> gh-7161 [/gh-7161/example.txt]")
 				.doesNotContain("WARNING:")
 				.doesNotContain("illegal")
 				.doesNotContain("jar written to temp");