JIRA: https://jira.spring.io/browse/INT-4265
* Add `.routeByError()` EIP-method to the `IntegrationFlowDefinition`
based on the `ErrorMessageExceptionTypeRouter`
* Add missed `dynamicChannelLimit()` option to the `RouterSpec`
* Rework `RouterSpec#RouterMappingProvider` into the `ContextRefreshedEvent`
phase initialization to be sure that dependent `MappingMessageRouterManagement`
is fully initialized before applying mapping conversions
* Rename `routeByError()` to `routeByException()` to more reflect reality
of the `ErrorMessageExceptionTypeRouter` and don't mislead about
Java's `Error`
* Polish `ErrorMessageExceptionTypeRouter` JavaDocs a bit and some Java 8
code style
* Add `ApplicationContext` assertion into the
`RouterMappingProvider.onApplicationEvent()` do not trigger delegate
initialization if `ContextRefreshedEvent` is from the different app context
f03356ccbc