Blog posts for patch releases can be two types:

* A blog post including bug and security fixes for the three versions
  included in the Maintenance Policy
* A blog post for a single version that only includes bug fixes.

The above lead to:
* Add a new method in the Coordinator class to determine if it corresponds to
  a single version
* A new method on the Coordinator class to determine the general patch
  release pressure
* Above methods were embedded on the blog post class to determine the
  blog post type: single or multiple versions, and to determine if the
blog posts include bug and security fixes.
* Additionally, since blog posts are always performed on the handbook
  repo, the `project` was transformed into an instance method and
removed as an argument.
* Specs and templates were updated to follow the new terminology

Related to https://gitlab.com/gitlab-com/gl-infra/delivery/-/issues/20052