When a survey's editing deadline has passed, show a clear message to the respondent

When a survey has a response editing deadline and that deadline has passed, respondents who view their response get no clear indication that it is no longer editable. This has caused confusion.

## Requested behaviour

When a respondent views a response after the editing deadline has passed, display a clear message explaining that the editing period has ended and the response can no longer be modified.

## Background

Requested in customer feedback.