[Desktop] Allow arrow key navigation for migrant selection page

[casillasenrique]

Describe the feature

"Nice to have" feature; allow arrow keys to control which migrant you want to select on the migrant select page.

Priority

0.5 (Nitpick)

Additional Notes and Information

A few participants from the user study used the arrow keys instinctually when seeing this migrant select page. This would be a nice feature particularly since it gives the simulation a more "game-like" feel, which may be more engaging.