Fixed EZP-20815: Enter key in setup wizard activates wrong action: back instead of next

JIRA: https://jira.ez.no/browse/EZP-20815

# Description

This patch fixes [EZP-20815](https://jira.ez.no/browse/EZP-20815) which has been there for [something like 10 years](https://jira.ez.no/browse/EZP-5592)... With this patch, you can now use "Enter" in the wizard forms to go to the next step.

phew! :)

# Tests

manual tests