Auto-select region settings according to language

Many people either lost time or started with the wrong keyboard because of a lack of correlation between the language and the rest. Changing the default keyboard and format based on the language would help. We’re doing this in the current Greeter and that was part of our plans anyway.

Feature Branch: greeter:feature/revamp_phase1

Parent Task: #10812 (closed)

Original created by @alant on 10815 (Redmine)