log: Add response content-type to access logs
This MR adds the HTTP response Content-Type
to access logs, using the content_type
key.
We're working on using LabKit's access logger in the GitLab Container Registry and this is the only field we're missing. The Container Registry API does a good amount of content negotiation/transformation around manifests and being able to see the response content-type is very useful to debug issues.
Edited by João Pereira