[web] Show password modal when pencil icon is clicked

Summary:
After the pencil icon is clicked, we setModal so that the password change modal is displayed.
Depends on D3476

Test Plan: Open account settings and click the pencil icon - the modal should be displayed. Check if clicking outside the modal and on x button closes the modal.

Reviewers: benschac, atul, def-au1t

Reviewed By: benschac, atul

Subscribers: ashoat, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3477