Add key navigation for search results

[FichteFoll]

Is your feature request related to a problem? Please describe

It is currently not possible to navigate the search results via keyboard only.

Describe the solution you'd like

I would like to use the arrow keys to move a visual indicator through the search results view, use the space key to select the indicated image for download, and use the enter/return key to open the preview for the indicated image.

Related to #1983.

[stale]

This issue has been automatically marked as stale because it has not had recent activity.
It will be closed if no further activity occurs.

If this issue is about a bug that still happens in the latest version, or a suggestion that is still relevant, feel free to comment on it and the maintainers will have another look, they might have missed it!

Thank you!