Update generated partner on next survey

This module links two survey features: the one that creates a contact from a survey and the one that generates answers. When a respondent who was created from a previous survey fills in a new survey, the answers are used to update the existing contact instead of creating a duplicate.

The update happens automatically when the survey response is marked as done. Only questions that are linked to a contact field are taken into account, and skipped questions are ignored. Answers that changed compared to the original survey are applied, as well as questions that did not exist in the first survey.

• Simple answers (text, number, date, single choice) overwrite the matching contact field.
• Multiple-choice answers linked to tags add the selected tags to the contact.
• Answers linked to a country or another record set that record on the contact.
• Free-text notes are appended to the contact's internal notes, together with the question title.
• If the survey is configured to create a parent contact, a company name answer updates the parent company's name; otherwise it is stored as the company name on the contact.

The module works on survey.user_input and relies on the contact-generation and answer-generation modules. It adds no new menus or screens; the behaviour is visible on the contact record after the survey is completed.