[TUI] Add back in 'Not staged for transfer' DirectoryTree styling

[JoeZiminski]

Currently not staged for transfer only works for rawdata / derivatives. However it would be nice to work for custom also. This will require refactoring utils/data_transfer.py to return the list of paths to transfer (it is currently an inflexible class) .

One approach is use this list of paths in update_transfer_tree and combine it with get_local_transfer_paths() to create the list to format.

Because this involes changes to both TUI and d.s. code it makes sense to wait until transfer tab is merged (or even tui-dev-branch).

[JoeZiminski]

• Handle tranfser tree highlighting (currently off by default)
• Test tranfser tree highlighting