German locale fixes for caravans

[phesch]

This PR aims to improve the German localization of the caravan strings by fixing some typos, improving consistency both internally and with the train GUIs of the base game, and adding strings for the recent additions (aerial fluid caravans and fill/empty until actions for fluids).
These translations were done manually by a native speaker (me), no AI involved.
If anyone has other suggestions for some of these strings, feel free to chip in!

[Spunk42]

hey nice, but you use the informal 2nd person form

confirm-deletion=Bist Du dir sicher?

this is somewhat inconsistent in other py-mods aswell, but i think "sie" is more often used?

[phesch]

Hi! I originally used the formal second person for those strings, but then I noticed that the base game uses the informal pronoun (specifically, I saw it used in the confirmation dialog when exiting to the main menu without saving the game first), so I changed the strings to match.
Personally, I would prefer the formal pronoun, but I think consistency is likely more important here. What do you think?
If it helps, I wouldn't be opposed to doing a sweep of all the German localization files for the Py mods and adjusting the pronouns to match everywhere - after all, it's mostly just a few s///g applications.

[Spunk42]

Personally, I would prefer the formal pronoun, but I think consistency is likely more important here. What do you think?

yes i agree, it seems like the base game doesnt use the formal form. But after a light skim through, it is sometimes inconsistent with an informal and a more passive tone. If you want you can sweep through the mods, but i have unfortunatly translated most with a formal or passive tone. And maybe all the declinations and more make s///g applications difficult.
anyway i will proceed to translate with a more passive and informal tone.