Consider implemented interfaces during `@Import` processing

[wilkinsona]

See spring-projects/spring-boot#45252 for background.

ConfigurationClassParser does not consider implemented interfaces when finding @Import (meta-)annotations. It would enable the scenario described in spring-projects/spring-boot#45252 if it did. I think it would also be more consistent with other areas of Framework where implemented interfaces are considered. The test context framework is one such area.