Create a report for Extension Points dump

We can for that reuse the code from apidoc-server, we basically need to extract a nuxeo-apidoc-model that would include:

• the api package
• the introspection package

Description of tasks:

• include apidoc explorer module features to create a report of extension point dumps, try to use the same version of all maintenance branches
• cleanup apidoc-core to avoid including unecessary deps (like document types specific to explorer needs)