Add ClassFile implementation for class metadata

Prior to this commit, Spring Framework would allow two ways of getting
class metadata:
* `StandardClassMetadata`, using the Java reflection API
* `SimpleMetadataReaderFactory`, using ASM to read the class bytecode

This commit adds a new implementation for this feature, this time using
the new `ClassFile` API which is taken out of preview in Java 24.

See gh-33616

spring-core/spring-core.gradle

@@ -11,7 +11,7 @@ apply plugin: "kotlin"
 apply plugin: "kotlinx-serialization"
 
 multiRelease {
-	targetVersions 17, 21
+	targetVersions 17, 21, 24
 }
 
 def javapoetVersion = "1.13.0"
@@ -25,6 +25,10 @@ configurations {
 	graalvm
 }
 
+springFramework {
+	enableJavaPreviewFeatures = true
+}
+
 task javapoetRepackJar(type: ShadowJar) {
 	archiveBaseName = 'spring-javapoet-repack'
 	archiveVersion = javapoetVersion