Serialize prompts that cycle through choices

[craffel]

In some prompt templates, there is logic like this:

      {% set seq = [

      ''Answer the question depending on the context.'',

      ''What is the answer?'',

      ] %}


      {{ seq | choice }}

      Context: {{context}};

      Question: {{question}};

...

This makes it so that one prompt is effectively multiple prompts. We should "serialize" them into separate templates.