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
Doc Polishing
e3f8ef534b