[web] Move code around to match the new code logic

Summary:
issue: https://linear.app/comm/issue/ENG-2739/move-navigationpanel-from-the-sidebar-to-a-top-bar
Now that the SettingSwitcher is no longer in the sidebar, it's code had to be moved outside of web/sidebar. The styles in left-layout-aside.css were only used for SettingsSwticher (and horizontal NavigationPanel that is used only in SettingsSwitcher so the file could be renamed and also moved. NavigationPanel is used for SettingSwitcher and AppSwitcher, so only for navigation panels. Thus all of this code could be put into web/navigation-panels as well as the Topbar, that is a navigation panel (contains AppSwitcher and will contain the navigation state information).

Test Plan: Run web app, check that the top bar in Inbox, and the SettingSwitcher in Settings display correctly. Run flow check in web/.

Reviewers: przemek, michal, bartek

Reviewed By: michal

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D6361