Add support for bean overriding in tests

This commit introduces two sets of annotations (`@TestBean` on one side
and `MockitoBean`/`MockitoSpyBean` on the other side), as well as an
extension mecanism based on the `@BeanOverride` meta-annotation.

Extension implementors are expected to only provide an annotation,
a BeanOverrideProcessor implementation and an OverrideMetadata subclass.

Closes gh-29917.

Author: simonbasle

Diff for: framework-docs/modules/ROOT/nav.adoc

@@ -183,6 +183,7 @@
 ***** xref:testing/annotations/integration-spring/annotation-sqlmergemode.adoc[]
 ***** xref:testing/annotations/integration-spring/annotation-sqlgroup.adoc[]
 ***** xref:testing/annotations/integration-spring/annotation-disabledinaotmode.adoc[]
+***** xref:testing/annotations/integration-spring/annotation-beanoverriding.adoc[]
 **** xref:testing/annotations/integration-junit4.adoc[]
 **** xref:testing/annotations/integration-junit-jupiter.adoc[]
 **** xref:testing/annotations/integration-meta.adoc[]

Diff for: framework-docs/modules/ROOT/pages/testing/annotations/integration-spring.adoc

@@ -28,4 +28,6 @@ Spring's testing annotations include the following:
 * xref:testing/annotations/integration-spring/annotation-sqlmergemode.adoc[`@SqlMergeMode`]
 * xref:testing/annotations/integration-spring/annotation-sqlgroup.adoc[`@SqlGroup`]
 * xref:testing/annotations/integration-spring/annotation-disabledinaotmode.adoc[`@DisabledInAotMode`]
+* xref:testing/annotations/integration-spring/annotation-beanoverriding.adoc#spring-testing-annotation-beanoverriding-testbean[`@TestBean`]
+* xref:testing/annotations/integration-spring/annotation-beanoverriding.adoc#spring-testing-annotation-beanoverriding-mockitobean[`@MockitoBean` and `@MockitoSpyBean`]