Add AopAutoConfiguration (also starter and sample)

A side effect is that spring-boot-starter-data-jpa needs
to include an aspectjweaver depdendency. Hope that doesn't
hurt anything else.

[Fixes #56780004]

spring-boot-starters/pom.xml

@@ -15,6 +15,7 @@
 	</properties>
 	<modules>
 		<module>spring-boot-starter</module>
+		<module>spring-boot-starter-aop</module>
 		<module>spring-boot-starter-batch</module>
 		<module>spring-boot-starter-data-jpa</module>
 		<module>spring-boot-starter-integration</module>