Acceptance criteria:
- File pages show the content split into sections for non-JS users
- File pages show the content split into tabs for JS users, without a FOUC
- First tab, labelled "File information", shows the captions block display/editor and the wikitext block
- Second tab, labelled "Structured data", shows the statements block display/editor – https://wikimedia.invisionapp.com/share/NJOIMI9D6SX#/screens/330580747
- No H1 heading any more
The file interaction block and the "what is metadata" information panel in the illustration are both out of scope.