Normalize pop-ups/modals/dialogs/messages for consistency throughout application

[jongranados]

Summary

Style pop-up modals/dialog boxes for consistency across app. Currently the app has a variety of alert messages appearing in different formats, including paragraph text and "toast" dropdown.

Acceptance Criteria

• The "Learn More" section on the Home page. Description and user instructions will open in dialog box after clicking on 'Learn More.'
• Replace 'toast' alert message on Home page with dialog box when user types in a token that does not exist.
• Replace the three possible messages on Add Item view that appear on screen with separate dialog boxes.

This issue is intended to be optional based on time and priority.