INT-2076 Polish (S)FTP Filter Docbook

JIRA: https://jira.spring.io/browse/INT-2076
INT-2974 Document Context Lifecycle + Fix

JIRA: https://jira.spring.io/browse/INT-2974
JIRA: https://jira.spring.io/browse/INT-3071
INT-2586 FTP Session Factory: Expose Timeout Props

JIRA: https://jira.spring.io/browse/INT-2586

Add timeout properties to the `DefaultFtpSessionFactory`
avoiding the need to subclass it just to set these
common properties.