Add (S)FTP source server information to messages

[garyrussell]

See https://stackoverflow.com/questions/57606912/spring-integration-java-dsl-sftp-how-to-get-remote-sftp-server-information-in-ha/57609407#57609407

[artembilan]

Migration Guide note: https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-5.1-to-5.2-Migration-Guide#sftp-session-gethostport-contract

[garyrussell]

I guess we will need an update to s-i-aws.

[artembilan]

an update to s-i-aws.

Will do today and comeback with some polishing if that. I somehow don't believe that I will be able to extract AWS port 😄