Migrate @Import classes to use constructor injection

[philwebb]

See spring-projects/spring-framework#23637

We may have a few *Aware based implementation that we can migrate.

[wilkinsona]

Some classes in the public API are potentially affected and I'm not sure how we should handle them. AbstractRepositoryConfigurationSourceSupport is one interesting example. If we change it to use constructor injection, all of its sub-classes will have to change too. Previously, they were unaware of their super-class's use of ResourceLoader, BeanFactory, and Environment.

[philwebb]

Interesting, I guess those might be better left as they are.