[web] Introduce settings switcher

Summary:
Render the first option from the switcher, currently not interactive
Depends on D3341

Test Plan: Render the component instead of AppSwitcher and check if it is displayed correctly. Manually switch between calendar and settings/account routes and check if the navigation option was highlighted only in the 2nd case

Reviewers: benschac, atul, def-au1t

Reviewed By: benschac, atul

Subscribers: ashoat, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3342