* INT-4544: Allow runtime MBeans (un)registered
JIRA: https://jira.spring.io/browse/INT-4544
* Fix `SourcePollingChannelAdapterFactoryBean` to register an
`outputChannelName` into the `SourcePollingChannelAdapter` for late
binding, especially in case of dynamic `IntegrationFlow` registrations.
This must be back-ported to `5.0.x`
* Implement `DestructionAwareBeanPostProcessor` in the
`IntegrationMBeanExporter` for the runtime beans tracking, e.g. via
dynamic `IntegrationFlow` registrations
* Refactor `IntegrationMBeanExporter` for static and dynamic beans
registration and destruction
* Remove unused properties; introduce some new for tracking beans and
their relationship
* * Move `IntegrationMBeanExporter.registerProducer()` after
`postProcessAfterInitialization()`
* Refactor JMX test configurations to reuse MBeanServer as much as
possible and destroy the server whenever it is necessary
* * More JMX tests polishing
* * And more JMX tests polishing
* * `try...catch` in the `IntegrationMBeanExporter.postProcessAfterInitialization()`
to avoid breaking changes for the current GA phase
* Do not unregister those MBeans explicitly which weren't created at
runtime
* * Log ObjectNames in the `MBeanExporterIntegrationTests`
* * Fix `MessageMetricsAdviceTests` to rely on the application context
* Do not use a cst in the `StandardIntegrationFlowContext` for
`BeanFactory`, but an explicit `BeanDefinitionRegistry`
* Extract targets from proxies in the
`IntegrationMBeanExporter.postProcessAfterInitialization()`
* Remove logging in the `MBeanExporterIntegrationTests`
* * Fix `NotificationListeningMessageProducerTests` to reuse existing `MBeanServer`
* * Change JMX `domain` in the `DslMBeanTests` to `dsl` do not clash with
similar in the `foo` in the `MessageSourceTests`
* Use `MBeanServer` bean in the `Int2307Tests`
* Use JUnit 5ctor injection injection in the `MessageMetricsAdviceTests`
* * Fix JMX tests do not reuse existing `MBeanServer` and make them rely
on the server provided by the managed `MBeanServerFactoryBean` which
destroys a server on application context close
* Fix `StoredProcJmxManagedBeanTests-context.xml` to use `MBeanServer`
from the `<context:mbean-server>`
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