Build up an index at runtime to remember which translations are missing and only log them once.
How to test
Go to the launcher settings and change the language.
Select a langauge with missing translations (German, French, and Italian definitely have missing translations for some labels).
The launcher log should print WARN logs about the missing translations only once.
Switching back and forth between those locales should not yield further log output.
Contains
Build up an index at runtime to remember which translations are missing and only log them once.
How to test
Go to the launcher settings and change the language. Select a langauge with missing translations (German, French, and Italian definitely have missing translations for some labels).
The launcher log should print WARN logs about the missing translations only once. Switching back and forth between those locales should not yield further log output.
Outstanding before merging
Based on #679.