Introduce predicate for searching enclosing classes in MergedAnnotations

[sbrannen]

Overview

Due to the deprecation of SearchStrategy.TYPE_HIERARCHY_AND_ENCLOSING_CLASSES (see #28079), we will introduce a way for users to provide a Predicate<Class<?>> that is used to decide when the enclosing class for the class supplied to the predicate should be searched.

This will give the user complete control over the "enclosing classes" aspect of the search algorithm in MergedAnnotations.

• To achieve the same behavior as TYPE_HIERARCHY_AND_ENCLOSING_CLASSES, a user can provide clazz -> true as the predicate.
• To limit the enclosing class search to inner classes, a user can provide ClassUtils::isInnerClass as the predicate.
• To limit the enclosing class search to static nested classes, a user can provide ClassUtils::isStaticClass as the predicate.
• For any other use case (such as in TestContextAnnotationUtils in spring-test), the user can provide a custom predicate.

Proposal

Based on the outcome of #28208, a searchEnclosingClass predicate could be supplied when using the TYPE_HIERARCHY search strategy as follows.

MergedAnnotations annotations = MergedAnnotations
    .search(SearchStrategy.TYPE_HIERARCHY)
    .withEnclosingClasses(ClassUtils::isInnerClass)
    .from(myClass);

By limiting when a searchEnclosingClass predicate can be supplied in the fluent search API, we can prevent users from trying to supply such a predicate for other SearchStrategy types.

[sbrannen]

Blocked until #28208 is implemented