Skip lazy init for beans that explicitly set lazy to false

This commit also adds tests to ensure that the child
management context works when lazy initialization is
enabled. Also, it adds a BeanFactoryPostProcessor to
the child context so that the server is created and
listening for requests but other beans in the child
context are not created until requested.

See gh-16184

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -119,6 +119,10 @@ on `SpringApplicationBuilder` or the `setLazyInitialization` method on
 	spring.main.lazy-initialization=true
 ----
 
+TIP: If you want to disable lazy initialization for certain beans while using lazy
+initialization for the rest of the application, you can explicitly set their lazy attribute
+to false using the `@Lazy(false)` annotation.
+
 
 
 [[boot-features-banner]]