Merge CI components and catalog docs

Problem

The https://docs.gitlab.com/ee/ci/components/ and https://docs.gitlab.com/ee/ci/components/catalog.html pages are currently separate but the instructions to get from an empty project to a catalog resource version published to the CI catalog can be out of order.

The project needs to be marked as catalog resource BEFORE a release being published otherwise a release will be created but nothing is displayed on the catalog. Also the CI Catalog docs are quite short currently and they are better merged with the CI components for now, to provide a complete description of the functionality.

As part of this change we can also make the following changes:

• rename components repository to component project: https://gitlab.com/gitlab-org/gitlab/-/issues/426730#note_1661682960
• revisit the terminology around releases to be more specific to catalog resource and the fact that release will be different than published versions in the future.