Support @⁠MockitoSpyBean at the type level on test classes

Prior to this commit, @⁠MockitoSpyBean could only be declared on fields
within test classes, which prevented developers from being able to
easily reuse spy configuration across a test suite.

With this commit, @⁠MockitoSpyBean is now supported at the type level
on test classes, their superclasses, and interfaces implemented by
those classes. @⁠MockitoSpyBean is also supported on enclosing classes
for @⁠Nested test classes, their superclasses, and interfaces
implemented by those classes, while honoring @⁠NestedTestConfiguration
semantics.

In addition, @⁠MockitoSpyBean:

- has a new `types` attribute that can be used to declare the type or
  types to spy when @⁠MockitoSpyBean is declared at the type level

- can be declared as a repeatable annotation at the type level

- can be declared as a meta-annotation on a custom composed annotation
  which can be reused across a test suite (see the @⁠SharedSpies
  example in the reference manual)

To support these new features, this commit also includes the following
changes.

- MockitoSpyBeanOverrideProcessor has been revised to support
  @⁠MockitoSpyBean at the type level.

- The "Bean Overriding in Tests" and "@⁠MockitoBean and
  @⁠MockitoSpyBean" sections of the reference manual have been fully
  revised.

See gh-34408
Closes gh-33925

framework-docs/modules/ROOT/pages/testing/testcontext-framework/bean-overriding.adoc

@@ -2,8 +2,8 @@
 = Bean Overriding in Tests
 
 Bean overriding in tests refers to the ability to override specific beans in the
-`ApplicationContext` for a test class, by annotating one or more non-static fields in the
-test class.
+`ApplicationContext` for a test class, by annotating the test class or one or more
+non-static fields in the test class.
 
 NOTE: This feature is intended as a less risky alternative to the practice of registering
 a bean via `@Bean` with the `DefaultListableBeanFactory`
@@ -42,15 +42,16 @@ The `spring-test` module registers implementations of the latter two
 {spring-framework-code}/spring-test/src/main/resources/META-INF/spring.factories[`META-INF/spring.factories`
 properties file].
 
-The bean overriding infrastructure searches in test classes for any non-static field that
-is meta-annotated with `@BeanOverride` and instantiates the corresponding
-`BeanOverrideProcessor` which is responsible for creating an appropriate
-`BeanOverrideHandler`.
+The bean overriding infrastructure searches for annotations on test classes as well as
+annotations on non-static fields in test classes that are meta-annotated with
+`@BeanOverride` and instantiates the corresponding `BeanOverrideProcessor` which is
+responsible for creating an appropriate `BeanOverrideHandler`.
 
 The internal `BeanOverrideBeanFactoryPostProcessor` then uses bean override handlers to
 alter the test's `ApplicationContext` by creating, replacing, or wrapping beans as
 defined by the corresponding `BeanOverrideStrategy`:
 
+[[testcontext-bean-overriding-strategy]]
 `REPLACE`::
   Replaces the bean. Throws an exception if a corresponding bean does not exist.
 `REPLACE_OR_CREATE`::