Create components-toolkit to test GitLab-maintained components

Summary

To extend further Create development guide for GitLab-maintained ... (#432768 - closed) and provide more explicit consistency we could create a component specific for testing GitLab-maintained components to ensure consistency and guide developers through CI failures. E.g. check that the LICENSE is added and is the correct one. Then developers would only need to include that in the .gitlab-ci.yml of the component project:

include:
  - component: gitlab.com/gitlab-org/components-toolkit/all-jobs.yml

Proposal

This could include various jobs. For example:

• job that tests that the LICENSE file is added and is correct.
• job that ensures the release tag follows semantic versioning and then creates a release automatically.
• job that ensures specific data is added to the README (e.g. ownership)