INT-3331: Add `ChannelSecurityInterceptorFB`

JIRA: https://jira.spring.io/browse/INT-3331

INT-3331: PR comments and others

* Register `ChannelSecurityInterceptorBeanPostProcessor` as a `BeanDefinition` (not `BPP`)
* Get `ChannelSecurityInterceptor`s from `ChannelSecurityInterceptorBeanPostProcessor#afterPropertiesSet()`
* Make `ChannelSecurityInterceptor` `final` to disallow to subclass it for unexpected issues
* Provide more convenience to the `ChannelSecurityInterceptorFactoryBean` - to allow to use it from xml configuration

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