style(EMS-4039): declarations - modern slavery - definition of terms

[ttbarnes]

Introduction ✏️

This PR updates the "declarations - modern slavery" page to contain some expandable content RE "definition of terms".

Resolution ✔️

• Update content strings.
• Move the cypress expandable selectors into a partial.
• Add E2E test coverage.
• Update the "expandable content" nunjucks component to be able to render nested children.
  • Previously, this only supported a list of single string list items.
  • Now, it can also support a single list item, with nested text and links inside the list item.
• Update nunjucks template.