DL-5823 Support legend with caption for input_radio.scala.html

[grahampaulcook]

DL-5823 Support legend with caption for input_radio.scala.html

New feature

If you are asking just one question per page as recommended, you can set the contents of the

as the page heading - https://design-system.service.gov.uk/

Rework to the input_radio.scala.html CTR component to display a caption with the H1 that the govukRadio component does not support directly.

https://github.com/hmrc/play-frontend-govuk/blob/master/src/main/twirl/uk/gov/hmrc/govukfrontend/views/components/govukFieldset.scala.html#L26

Checklist

• [ ] I've made every effort to commit high quality, clean code and I have executed relevant static analyses to be sure
• [ ] I've included appropriate tests with any code I've added (Unit, Integration, Acceptance etc.)
• [ ] I've executed the acceptance test pack locally to ensure there are no functional regressions
• [ ] I've added my code using logical, atomic commits, squashing as appropriate - including the JIRA issue number in the commit message
• [ ] I've run a dependency check to ensure all dependencies are up to date