Improve usability of Directory datatype

[wm75]

This adds functionality to the Directory datatype class, which can now be displayed and downloaded as an archive. It also adds a new archive_to_directory converter that generalizes the existing tar_to_directory one to work with tar and zip archives. Also updates the older converter's requirement to an existing version of the galaxy-util package. Previously the exact requirement wasn't installable via conda.

How to test the changes?

(Select all options that apply)

• [ ] I've included appropriate automated tests.
• [ ] This is a refactoring of components with existing test coverage.
• [x] Instructions for manual testing are as follows:
  1. upload an archive as either zip or tar
  2. convert the datatype to directory
  3. explore

License

• [x] I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.