Add missing translations for different languages

[crdgonzalezca]

In Spanish there are some left messages not being translated for certain plugins:

• Problem bank
• Grader

In English:

• Data policy (The text must be marked to translate and translate to English).

Languages with many messages not translated yet:

• German
• French
• Portuguese

Additional context
Here is documentation about i18n.

[AndresFelipeCastellanos]

Some messages on data policy, course and task administration need to be translated for the Portuguese, French, and German languages. Some inner elements on course administration scripts do not have yet translations on those languages.