[web] Add navigation path for account settings

Summary: The idea here is to introduce a new path settings under which there will be located all the settings (things that are displayed when a user clicks a cog icon in https://www.figma.com/file/a1nkbWgbgjRlrOY9LVurTz/Comm-%2F-Desktop-app?node-id=1272%3A88750).

Test Plan: The behavior should be the same after this diff. Tested in combination with the next one.

Reviewers: benschac, atul, def-au1t, ashoat

Reviewed By: benschac, ashoat

Subscribers: ashoat, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3335