Track interface implementors

[sebersole]

Similar to what we do with ClassDetailsRegistry#getDirectSubTypes we should consider adding a mapping of interfaces to direct-impls.

[sebersole]

Turns out, once we have (direct) interface implementors along with the already existing direct subtypes we can implement cool things like walking/collecting all implementors or concrete types from a base type...

public interface ClassDetailsRegistry {
	...
	Set<ClassDetails> getDirectImplementors(String interfaceName);
	void forEachDirectImplementor(String interfaceName, ClassDetailsConsumer consumer);

	Set<ClassDetails> findConcreteTypes(String base, boolean includeBase);

	void walkImplementors(String base, boolean includeBase, ClassDetailsConsumer consumer);
	Set<ClassDetails> collectImplementors(String base, boolean includeBase, Predicate<ClassDetails> exclusions);

	default Set<ClassDetails> findConcreteTypes(String base) {
		return findConcreteTypes( base, true );
	}

	default Set<ClassDetails> collectImplementors(String base, boolean includeBase) {
		return collectImplementors( base, includeBase, null );
	}
}