Rename spring-boot-loader to spring-boot-loader-classic

Rename the `spring-boot-loader` module to `spring-boot-loader-classic`
so that we can introduce an alternative loader implementation.

See gh-37669

spring-boot-tests/spring-boot-integration-tests/spring-boot-loader-classic-tests/build.gradle

@@ -4,7 +4,7 @@ plugins {
 	id "org.springframework.boot.integration-test"
 }
 
-description = "Spring Boot Loader Integration Tests"
+description = "Spring Boot Classic Loader Integration Tests"
 
 configurations {
 	app
@@ -28,13 +28,13 @@ task syncMavenRepository(type: Sync) {
 }
 
 task syncAppSource(type: org.springframework.boot.build.SyncAppSource) {
-	sourceDirectory = file("spring-boot-loader-tests-app")
-	destinationDirectory = file("${buildDir}/spring-boot-loader-tests-app")
+	sourceDirectory = file("spring-boot-loader-classic-tests-app")
+	destinationDirectory = file("${buildDir}/spring-boot-loader-classic-tests-app")
 }
 
 task buildApp(type: GradleBuild) {
 	dependsOn syncAppSource, syncMavenRepository
-	dir = "${buildDir}/spring-boot-loader-tests-app"
+	dir = "${buildDir}/spring-boot-loader-classic-tests-app"
 	startParameter.buildCacheEnabled = false
 	tasks  = ["build"]
 }

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

@@ -71,7 +71,7 @@ class LoaderIntegrationTests {
 	}
 
 	private File findApplication() {
-		String name = String.format("build/%1$s/build/libs/%1$s.jar", "spring-boot-loader-tests-app");
+		String name = String.format("build/%1$s/build/libs/%1$s.jar", "spring-boot-loader-classic-tests-app");
 		File jar = new File(name);
 		Assert.state(jar.isFile(), () -> "Could not find " + name + ". Have you built it?");
 		return jar;