Implement the new native designs for the nav bar

This should be behind the new navigation feature flag setup for the front end

Top nav

• New title on the top left
• Messenger icon with notifications
• Search button

Bottom nav

• Home button

changed the description

changed weight to 8

assigned to @juanmsolaro

changed milestone to %Sprint::01/15 - Youthful Yabby

changed due date to January 28, 2020

added scoped labels

added scoped label

added to epic &93