Support generating both bilingual and translated-only outputs for each translation

Currently, bilingual_book_maker supports two modes:

• Bilingual translation (original + translated)
• Single translated-only output (translated text only)

Can we add support for generating both outputs at the same time for each translation? That is, for each translation, output two files:

• One file with bilingual (original + translated) content
• One file with translated-only content

This would make it more convenient to get both formats without running the translation process twice.

Thanks!