Bug: Add a "Could Not Find Repo" message to workspace repo import

[BekahHW]

Describe the bug

As far as I can tell, if the search can't find a repo when trying to import a repo in a workspace, the loader continues to spin.

It would be useful to have some indication that the repo can't be found rather than continuing to run the loading icon.

https://github.com/open-sauced/app/assets/34313413/d4a9e8ff-b711-4ce9-86b3-befe0b9e92cb

Steps to reproduce

1. Go to this workspace: https://app.opensauced.pizza/workspaces/79f026cd-4a32-43e7-a8b7-ea6e2b67333f
2. click edit
3. click add repositories
4. Try to add octokit/core.js