Similar to what we did in PR "Avoid duplicate records in poll answers" 5539,
specifically in commit 503369166, we want to stop relying on the plain text
"answer" and start using "option_id" to avoid issues with counts across
translations and to add consistency to the poll_partial_results table.
Note that we also moved the `possible_answers` method from Poll::Question to
Poll::Question::Option, since the list of valid answers really comes from the
options of a question and not from the question itself. Tests were updated
to validate answers against the translations of the assigned option.
Additionally, we renamed lambda parameters in validations to improve clarity.
Note that we have the same code in the officing section.
Then we can use the same component.
Note also that we are removing the parts of the system specs that are now
covered by the component itself, and taking the chance to unify tests.
In these removals and unifications we take into account that there are
other specs which already cover user interaction in this section.
