JIRA: https://jira.spring.io/browse/INT-4154
* Move `Transformers` for files to the `Files` factory
* Remove `@Deprecated` methods
* Fix `FilesTests` for new packages and removed methods like `.handleWithAdapter()`
Provide JavaDocs for File DSL and implement some new methods like `chmod()` and `renameFunction()`
Fix race condition in the `ScriptsTests` when even small time window delay may lead us to one more message in the queue