Spring Framework 4.2 RC1 introduced support for synthesizing an
annotation from an existing annotation in order to provide additional
functionality above and beyond that provided by Java. Specifically,
such synthesized annotations provide support for @AliasFor semantics.
As luck would have it, the same principle can be used to synthesize an
annotation from any map of attributes, and in particular, from an
instance of AnnotationAttributes.

The following highlight the major changes in this commit toward
achieving this goal.

- Introduced AnnotationAttributeExtractor abstraction and refactored
  SynthesizedAnnotationInvocationHandler to delegate to an
  AnnotationAttributeExtractor.

- Extracted code from SynthesizedAnnotationInvocationHandler into new
  AbstractAliasAwareAnnotationAttributeExtractor and
  DefaultAnnotationAttributeExtractor implementation classes.

- Introduced MapAnnotationAttributeExtractor for synthesizing an
  annotation that is backed by a map or AnnotationAttributes instance.

- Introduced a variant of synthesizeAnnotation() in AnnotationUtils
  that accepts a map.

- Introduced findAnnotation(*) methods in AnnotatedElementUtils that
  synthesize merged AnnotationAttributes back into an annotation of the
  target type.

The following classes have been refactored to use the new support for
synthesizing AnnotationAttributes back into an annotation.

- ApplicationListenerMethodAdapter
- TestAnnotationUtils
- AbstractTestContextBootstrapper
- ActiveProfilesUtils
- ContextLoaderUtils
- DefaultActiveProfilesResolver
- DirtiesContextTestExecutionListener
- TestPropertySourceAttributes
- TestPropertySourceUtils
- TransactionalTestExecutionListener
- MetaAnnotationUtils
- MvcUriComponentsBuilder
- RequestMappingHandlerMapping

In addition, this commit also includes changes to ensure that arrays
returned by synthesized annotations are properly cloned first.

Issue: SPR-13067