Configure reports.ofsted.gov.uk as alias to main site

reports.ofsted.gov.uk is a holding location for Ofsted inspection reports. It is a direct lift of content formerly at www.ofsted.gov.uk but is likely to be redeveloped in the next 1-2 years. When repointed to GOV.UK, this subdomain should be treated as a (partial) alias of www.ofsted.gov.uk, and [these bouncer rules](https://github.com/alphagov/bouncer/blob/master/lib/bouncer/preemptive_rules.rb#L22-28) should be amended to work with its replacement service.