INT-2126/2871/2877/2872

Pushed as a single PR because of conflicts - suggest reviewing the 4 commits individually.

The first commit is the biggest; the rest are relatively minor.

1. Add TCP connection application events as well as `<tcp-event-inbound-channel-adapter/>`
2. Provide a mechanism to query a connection factory for open connection ids, and the ability to close a connection by id.
3. Refactoring - specifically the TcpMessageMapper to make it easier to subclass, and inject a custom implementation.
4. Remove TCP deprecations.