Use presenters instead otherwise we will have x2 overides in EE

Refacotr project or group specific `if` logic to be contained within
each presenter instead.

Also add :override to ensure super method exists.

Use model method as single source of truth instead of splitting between
presenter and Kubernetes model

Group clusters should not allow Project Namespace so don't show that
field input too

Based on BE reviewer feedback

As the frontend is still in progress and other related backend is still
in prgress we need a feature flag to turn off Group Clusters.

These applications will need further work in future issues to enable
them to work with groups of projects.

Remove the requirement to have actual_namespace before using kubeclient.

- Add pages javascripts to intialize clusters for group pages

- Move specs asserting gcp specific validations from controller into
UpdateService spec

- Also teach Clusters::ApplicationController about groups

As this is the only item in this menu, make Kubernetes the link for the
sidebar item too.

- maintainer for group can read, create, update, and admin cluster
- project user, at any level, cannot do anything with group cluster

Fix for the filter spec failure

Closes gitlab-org/quality/nightly#34 and gitlab-org/quality/nightly#30

See merge request gitlab-org/gitlab-ce!22862

Adds documentation for restricted project service account in deployment jobs

Closes #51717

See merge request gitlab-org/gitlab-ce!22810

Document that we do not support importing bare repositories from hashed storage in certain cases

Closes #41423

See merge request gitlab-org/gitlab-ce!22783

Add e2e test of push over SSH using Git protocol v2

See merge request gitlab-org/gitlab-ce!22548

Emphasis the importance of auth registry

See merge request gitlab-org/gitlab-ce!22843

StuckImportJobsWorker query performance optimization

See merge request gitlab-org/gitlab-ce!22879

Adds a btn-icon class

See merge request gitlab-org/gitlab-ce!22870