Fixes: #9123
The `/` at the beginning of the remote dir path is not necessary when listing files, although it is necessary to download them
The `SftpTemplate.get()` should work also with `remote-dir/MyFile.csv` as input.
* Fix `SftpSession.readRaw()` to call `sftpClient.canonicalPath(source)` if the path does not start with a `/`.
Something similar what is does
* Delegate to `SftpSession.readRaw()` from the `SftpSession.read()`
* Reuse `normalizePath()` for `doList()`
**Auto-cherry-pick to `6.2.x` & `6.1.x`**
a2215afdf7