Reuse i18n messages and use right submit label

Authored by WMDE-Fisch on Wed, May 3, 11:43 AM.

Description

Reuse i18n messages and use right submit label

The label of the submit button can differ depending on a conf setting.
The extension should use the label fitting that setting.

Bug: T164151
Bug: T162775
Change-Id: Ib09c4c6af39067d783442f0a7d229634d835a6b3