Given these are shown to the user, they should be translatable.

While we're at it, also set up the dialog to automatically retranslate
the dialog along with the combo boxes if it receives a LanguageChange
event.

Keeps the individual initialization of the combo boxes logically separate.
We also shouldn't be dumping this sort of thing in the constructor
directly.

This makes clang-format useful on those.

Also add a bunch of forgotten transitive includes, which otherwise
prevented compilation.