QuestionnaireResponse narrative generation

[liambarnes]

Describe the bug

1. Nested repeat groups are not supporting in narrative.
   QuestionnaireResponse.text.div does not provide the right information and therefore the preview screen also does not display correct info (see image)

2. Narrative also does not include units for decimal/integer types (see image). Units are not included in the QuestionnaireResponse as these are not answer values. They are defined in the Questionnaire and are what the renderer use to display the correct units.

3. Narrative uses non-conformant HTML elements for XHTML

To Reproduce

1. Launch GPCCMP with context
2. Open previous response - I've saved a draft QuestionnaireResponse demonstrating this (also attached)

QuestionnaireResponse-974.json

Expected behavior

1. text.div and narrative display should contain the data in the structured QuestionnaireResponse and provide the user with a usable view even when nested repeat groups.
2. text.div and narrative display should contain any relevant units as displayed in the rendered form.
3. Only XHTML elements are used.