Add CommentAnnotation(ns=`.../fileTransfer`) with class of FT

With this change, an annotation is added to the `Fileset` object
on import describing which `FileTransfer` implementation was used.

Use of the default `UploadFileTransfer` is ignored; otherwise, the
FQN is stored as the content of the annotation. If we decided to
move to subclasses of `Fileset` these values should suffice.

Representative output after an import includes:

```
ome2=> \x
ome2=> select discriminator, id, ns, textValue from annotation order by id desc limit 2;
-[ RECORD 1 ]-+---------------------------------------------------
discriminator | /type/OriginalFile/
id            | 3102
ns            | openmicroscopy.org/omero/import/logFile
textvalue     |
-[ RECORD 2 ]-+---------------------------------------------------
discriminator | /basic/text/comment/
id            | 3101
ns            | openmicroscopy.org/omero/import/fileTransfer
textvalue     | ome.formats.importer.transfers.SymlinkFileTransfer
```
Fix 'tranasfer' typo