Pontoon: Update Vietnamese (vi) localization of AMO Frontend
Pontoon: Update Vietnamese (vi) localization of AMO Frontend

Localization authors:
- Nguyễn Xuân Minh <mxn@1ec5.org>
- Pierre Neter <pierreneter@gmail.com>

kumar303/addons-frontend,mozilla/addons-frontend,kumar303/addons-frontend,tsl143/addons-frontend,mozilla/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,mozilla/addons-frontend,tsl143/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,tsl143/addons-frontend,tsl143/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,mozilla/addons-frontend,kumar303/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,kumar303/addons-frontend