* GH-3572: Migrate SFTP from `jsch` to `sshd-sftp`
Fixes https://github.com/spring-projects/spring-integration/issues/3572
* Rework SFTP module from the JSch API to more modern `sshd-sftp`
* Migrate generics of most API from `ChannelSftp.LsEntry` to the `SftpClient.DirEntry`
* Rework `DefaultSftpSessionFactory` to deal with an `SshClient` and create `SftpClient`
wrapped to the `SftpSession`
* Implement a `ResourceKnownHostsServerKeyVerifier` to load `known-hosts` from any possible resource
* Implement an expected `SftpSession.list()` with just file name to take or pattern matching
* Remove some unused tests and their config
* Remove tests for custom `UserInfo` since we don't provide any custom out-of-the-box
* Test a new `ResourceKnownHostsServerKeyVerifier` against default `known-hosts` file
* * Some tests improvements
* * Improve generics handling for `FileUtils`
4aa2f91bd9