DL-6208 - H1 Header spacing changes

some unit tests were still using the old helpers, changed them to new migration ones
text-expander error messages didn't link to input fields when a radio button was unselected, amended ids
removed hmrcPageHeading and replaced with components for headings and captions
changed component labels to strings, as play-frontend wraps the content in a h1 which caused spacing issues

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