Co-authored-by: Mario Squeo <msqueo@osc.edu>

UI for the files app with buttons for various actions not yet implemented

basic implementations for:

1. Open In Terminal
2. Show Dotfiles and Show Owner/Mode (Mario)
3. Filter box clearing on navigating to new directory (Mario)
4. Change directory via AJAX by selecting directory, clicking up, or specifying path in Change directory dialog
5. Copy path button
6. Sorting by Size and Modified at (Mario)

Co-authored-by: Mario Squeo <msqueo@osc.edu>

- Transfer resource allows executing the action synchronously or asynchronously via ActiveJob
- When using ActiveJob we use Rails built in support for GlobalID of the Transfer object
- Transfer manages its own in memory array of Transfer objects
- Client side, each transfer that is asynchronous has its own polling cycle
- Server side validations are enforced using ActiveModel validations
- System tests are added for end to end testing

Directory uploads include empty dirs only when a directory upload is initiated via drag and drop

This is due to HTML5 limitations

When using an <input type="file" webkitdirectory> you get back a FileList of File objects
When using drag and drop you get a transfer object that gives you access to the File and Directory Entries API