Expose registrar for @Reflective

This commit exposes the logic of processing `@Reflective` on beans so
that it can be reused in custom arrangements.

Closes gh-28975

spring-context/src/main/resources/META-INF/spring/aot.factories

@@ -1,3 +1,5 @@
+org.springframework.beans.factory.aot.BeanFactoryInitializationAotProcessor= \
+org.springframework.context.aot.ReflectiveProcessorBeanFactoryInitializationAotProcessor
+
 org.springframework.beans.factory.aot.BeanRegistrationAotProcessor= \
-org.springframework.context.aot.ReflectiveProcessorBeanRegistrationAotProcessor,\
 org.springframework.cache.annotation.CachingBeanRegistrationAotProcessor