[web] Open block list when user clicks a button

Summary:
After user clicks a block list button on account settings page, display a modal with all the blocked users.

Depends on D4038

Test Plan: Click the button on account settings page and check if the modal is displayed.

Reviewers: benschac, atul, def-au1t

Reviewed By: atul

Subscribers: ashoat, Adrian, yayabosh

Differential Revision: https://phabricator.ashoat.com/D4039