Add translation resources for alerts (or dismiss alerts)

[norbertschuler]

Describe the feature you'd like to see included in Tree Mapper App.

Check which alerts are necessary and do not yet have a translation:

• delete unnecessary alerts or replace them with (db) logging
• add translation resources where alerts should really show something to the user

[norbertschuler]

Not yet translated resources in alerts are marked with the comment TODO:i18n.