[native] Style the navigation drawer (all labels the same)

Summary:
Linear issues: https://linear.app/comm/issue/ENG-2397/community-drawer-colours
https://linear.app/comm/issue/ENG-2343/style-the-navigation-drawer-on-native
https://linear.app/comm/issue/DES-10/design-for-light-mode-on-native

Designs: https://www.figma.com/file/WmS4u84vnveHHCcZusn5A4/%E2%9A%A1%EF%B8%8F-Mobile-App-Sidedrawer?node-id=4429%3A32903&t=tqg2p8kNEmavnWil-0
https://www.figma.com/file/L675ETKDnGaSwlpZAw4MIC/Mobile-App?node-id=3598%3A52104&t=SscXfXRNOzPWSkDp-0

I realised thanks to the light mode designs that drawer item labels on different levels are supposed to be styled differently. This will require a non-trivial amount of changes, so I'll do this in the
next diff. In this diff all labels are styled like the items representing communities.

HitSlop on TouchableOpacity for expand buttons were determined by testing on physical devices.

Test Plan: Run app on multiple simulators and physical devices and see if all looks good.

Reviewers: ginsu, bartek, tomek

Reviewed By: bartek, tomek

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D5866