[web] Open SidebarsModal instead SidebarListModal on web

Summary: The diff replaces an old sidebar list modal with the new one after clikcing in thread top menu and after clikcing "see more sidebars"

Test Plan: Modal should be opened in "All threads" tab from menu and in "My threads" from "see more sidebars" button. Searching sidebars should be possible.

Reviewers: tomek, atul

Reviewed By: tomek

Subscribers: ashoat, adrian, abosh

Differential Revision: https://phab.comm.dev/D4611