Spring Add support for BeanRegistrar implementing RuntimeHintsRegistrar

Would be useful for native-compliant classpath checks described in https://github.com/spring-projects/spring-framework/issues/21497 for example, but likely also for other use cases.

Comment From: sdeleuze

I am not sure we can easily support BeanRegistrar implementing RuntimeHintsRegistrar with the GenericApplicationContext#register use case, so I will decline this issue, as there are alternative ways to declare RuntimeHintsRegistrar (META-INF/spring/aot.factories or @ImportRuntimeHints).