[web] Remove usage of setTab and replace with setCurrentTabType

Summary:
Remove setTab since it's no longer necessary and replace usages with setCurrentTabType which does the exact same thing.

As part of the work to refactor ThreadSettingsModal... specifically to turn it into a functional component.

Depends on D3763

Test Plan:

1. Open ThreadSettingsModal
2. Switch between tabs as before

Reviewers: palys-swm, def-au1t

Reviewed By: palys-swm

Subscribers: ashoat, Adrian, karol-bisztyga, benschac, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3764