[web] introduce light mode to settings switcher
Summary:
This diff introduces the new color design system/light mode to the settings switcher component.
For additional context about this new color design system and the new naming convention here is the notion doc:
https://www.notion.so/commapp/New-Color-System-Proposal-ef80b4e4b9ec42949095056161223a42
Depends on D9837
Test Plan:
Please see the screenshots below
light:
dark:
Reviewers: atul, inka, rohan
Reviewed By: atul
Subscribers: ashoat, tomek, wyilio
Differential Revision: https://phab.comm.dev/D9838