[Task]: Add arrow key support for dropdowns

[maxwellmattryan]

Task description

Having arrow key support for dropdown inputs would be really nice 🙏

Requirements

• Add arrow key support for dropdowns
• Add sensible styling for highlighted option
• Check dropdowns throughout the app (recipient for sending, node URL for proposals, etc.)

Creation checklist

• I have assigned this task to the correct people
• I have added the most appropriate labels
• I have linked the correct milestone and/or project