GitLab Operator: remove the dependency on GitLab Helm Charts
## Summary
The current GitLab Operator (V1) is tightly coupled to GitLab Chart and we want to remove that dependency. For a background and supporting discussion see [this issue](https://gitlab.com/gitlab-org/distribution/team-tasks/-/issues/990).
To achieve this, GitLab Operator V2 installs and upgrades a [minimum GitLab instance](https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/issues/1508) with loose or no dependency to GitLab Chart.
## Objectives
- Define the scope of a _minimum GitLab instance_.
- Install and upgrade a _minimum GitLab instance_ using the new GitLab resource specification, i.e. `v2beta1`.
- Offer a roadmap to add support for more GitLab features and components.
## Success Criteria
- Shared secrets are created by GitLab Operator.
- Core components of the _minimum GitLab instance_ are managed by GitLab Operator.
- GitLab Operator V2 can install a new _minimum GitLab instance_.
- GitLab Operator V2 can upgrade an existing _minimum GitLab instance_.
- The Operator no longer depends on the GitLab Helm Charts
epic