Translation: Request new translation if required

Depends on #9

# Description

This is a follow-on from #9, which implemented on-demand translation of content. This ticket did not account for scenarios where the base content is updated after the translation has been created.

Update the function to check for two conditions: first, the existence of a translation, and second, whether the base content has been updated since that translation was created. If the base content is newer, a new translation should be requested.

# Acceptance criteria

- [ ] If the base content has been updated since the translation was created, a new translation should be requested and patched/returned accordingly.
- [ ] If the base content has not been updated since the translation was created, the existing translation should be returned as-is.