Enable ahead-of-time compilation

[bahnson]

Steps to reproduce missing AOT-support:

1. Take spring boot app that uses EntityGraphJpaRepository e.g. @Repository public interface MyGraphRepository extends EntityGraphJpaRepository<MyEntity, UUID>, EntityGraphJpaSpecificationExecutor<MyEntity>{}
2. Build with ahead-of-time compilation: mvn -q -DskipTests compile spring-boot:process-aot package
3. See logs: you'll get org.springframework.data.core.PropertyReferenceException: No property 'findAll' found for type 'MyEntity'

Solution would involve:

• adapting RepositoryFactoryBean
• registering repository fragments early
• adding AOT contributions via AotRepositoryContext