Move translations of chart keys to the ChartsConfigurationsConcern

We have to translate the keys anyway. This way we'll a single point where the translations happen. Also, it will make my life easier now that I'll start adding the charts in the dynamic section. Instead of having to find out which chart was selected and making the translations, it's easier to just send everything translated and do less processing in view and JS.

Next steps are to add the translations for the remaining charts that need it, and dynamically build them in the dynamic section.

Part of #71 (closed)