[web] [refator] Chat thread list

Summary: destructure item a bit more. No new functionality.

Test Plan: make sure thread item still works.

Reviewers: atul, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3184