[web] Restyle ThreadSettingsDeleteTab
Summary:
There aren't any designs for this in Figma, so tried to get close to what we have in ThreadSettingsGeneralTab. There's definitely room to improve the design here, this was strictly a first pass.
Depends on D4018
Test Plan:
Before (start of stack):
After: (after this diff):
Reviewers: def-au1t, palys-swm, benschac
Reviewed By: palys-swm, benschac
Subscribers: ashoat, Adrian, yayabosh
Differential Revision: https://phabricator.ashoat.com/D4019