Add multi language support

[jfreissmann]

Description of task

The simulation dashboard was not built for a wider audience from the start. That is reason a lot of text still is in german. On the other hand, the heap pump model classes are mostly using english, so we are not even consistent with german. The task for this issue is to implement a user selectable language, which is the dynamically applied to all text within the dashboard.

Necessary steps

• Existing german text has to be translated to english and vice versa
• Some kind of button or switch has to be added to the dashboard to toggle between languages
• Text has to be dynamically chosen based on language switch