[lib] Create hooks for common DisconnectedBar logic for web and native

Summary: Created hooks with common logic for web and mobile app.

Test Plan: Tested the hooks on mobile and web (in the next diffs)

Reviewers: palys-swm, benschac, atul, ashoat

Reviewed By: palys-swm, benschac, ashoat

Subscribers: ashoat, Adrian, atul, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D2848