Refactor custom directory components for reusability, override worker directory

[dremin]

Summary

Now if someone wants to add their own tab, it is much easier:

• There is a common DirectoryTab component that includes all of the layout and search logic.
• There is a common DirectoryItem component for rows in DirectoryTab
• Now to add a new tab, just pass an array of DirectoryEntry objects, and a transfer function, to DirectoryTab

Added a custom worker directory tab to complement the queue tab. Now the worker tab can filter unavailable agents, and has the correct icons per media type.

Checklist

• Tested changes end to end
• Requested one or more reviewers

[github-actions]

0 ESLint error(s) and 0 ESLint warning(s) found in pull request changed files.
0 ESLint error(s) and 0 ESLint warning(s) found in files outside of the pull request.

✅ No issues found!

[jared-hunter]

Looks great, i love the refactor - some minor updates to tackle plus an optional item on the no items label

I think we want to update the documentation too, to conform to the broader standard but we can do that as part of a separate effort.

[jared-hunter]

Awesome work!