Add an integration test for industry sectors

This currently relies on the 'content-api-moar-test-helpers' branch in
gds-api-adapters.
Add tests and Slimmer headers for industry sectors
Tweak the design and layout of industry sectors

This makes them look a bit more like the business browse page.
Add report-a-problem to the sector pages
Bump gds-api-adapters to 8.2.3

This includes fixes for the Content API test helpers.