Suport for child context creation during AOT processing

[lgklein]

Based on spring-cloud/spring-cloud-commons#1135...

[lgklein]

@OlgaMaciaszek this enhancement should by moved to 4.0.0-RC1? Asking because 4.0.0-M5 was already closed but this issue still open

[OlgaMaciaszek]

Yes, I've moved it.