WIP: Upload the lint Docker image in the Registry

This is going to replace https://gitlab.com/gitlab-org/gitlab-build-images/blob/master/Dockerfile.gitlab-docs-lint.

For #306 (closed).

We need to be sure this works as intended in the respective projects the docs lint is run.

The following issue needs to be resolved before we get this MR in:

• Create parallel jobs for internal links testing #308 (closed)