Multilingual configuration + Missing translations

[janezd]

Description of changes

Add missing translations. Add configuration for multiple languages.

Includes

• [X] Code changes

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.26%. Comparing base (d8818b5) to head (771f085). Report is 40 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6828 +/- ## ========================================== + Coverage 88.22% 88.26% +0.03% ========================================== Files 327 326 -1 Lines 71273 71158 -115 ========================================== - Hits 62883 62809 -74 + Misses 8390 8349 -41 ```