Investigate better ways of storing/editing code snippets than the yaml file

Keeping code snippets in the yaml file makes it very hard to edit and write due to needing to put escape characters for new lines and having to handle indenting manually, and no syntax highlighting/checking. Maybe we could put the code snippets in their own file and link them to the questions definition somehow?

Locate the YAML file that stores the code snippets and inspect how the questionnaire definitions currently reference or load them. Compare possible storage and editing approaches, including how multiline content and syntax checking would work. Done means documenting a concrete approach that improves editing while preserving the link between snippets and questions.

Written by the indexing model from the issue text.