Any resources created while the cluster was managed
will be untouched, allowing users to set/unset this
flag as they please.

Instance level clusters were already mostly supported, this change adds
admin area controllers for cluster CRUD

When this option is enabled, GitLab will create namespaces and service
accounts as usual. When disabled, GitLab wont create any project
specific kubernetes resources

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/56557

- rewords examples starting with 'should'
- rewords examples starting with 'it'

Note: I had to manually fixup "onlies" to "only"

- Fixes multiple typos on AutoDevops script
- Add an alias to Clusters::Cluster#domain as base_domain, so it's more
descriptive
- Removes unnecessary memoization on qa specs
- Changes migration to a post migration to deal better with traffic on
big instances (like gitlab.com)

Changes domain field to be on the Cluster page show, removing it from
Auto DevOps setting. Also injects the new environment variable
KUBE_INGRESS_BASE_DOMAIN into kubernetes#predefined_variables.

Migration to move the information from ProjectAutoDevops#domain
to Clusters::Cluster#domain. As well as necessary modifications to qa
selectors

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/52363

Updates specs to use new rails5 format.

The old format:
`get :show, { some: params }, { some: headers }`

The new format:
`get :show, params: { some: params }, headers: { some: headers }`

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.

- 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

Use ClustersController as base while having Projects::ClustersController
to inform what `clusterable` is. Thanks @ayufan for the great suggestion
!

- View changes to work with new approach

- Fix javascript for new approach

- Fix feature specs for new approach

- Fix QA

To the extent possible swap out `project` with `clusterable`

- Abstract paths for showing cluster or clusters. This will allow us to
swap in alternative paths for group level cluster

- Push :project_id and :namespace_id params from the URL to the POST
body.

- Create a nice helper for to generate links for the destroy
action

For some reason, spec :project_id and :namespace_id param are not going
through `to_param` for a JSON format. Manually call `to_param` to fix
specs.

- Move :layout to BaseController

In preparation so that we can create both cluster attached to project
and cluster attached to group.

- Move ClustersController to top level

- Move Clusters::ApplicationsController to top-level too

- Creates a Clusters::BaseController to share common functions

- Do not rely on @project ivar. Anything could set the ivar.

- Fix Vue page components due to new data-page value

Because of the controller change we have gone from
`projects:clusters:new` to `clusters:new`, so we need to update the file
location of the page components. There is somewhere a function that will
convert data-page to a file location.

On that note, projects/clusters/gcp/new/, translate to
Projects::Clusters::Gcp#new doesn't exist so replace that with
clusters/create_gcp/ and clusters/create_user/

It has been pointed out that `go` is used quite extensively so it's not
an unknown idiam here at GitLab. And we have arguments with `go` which
is a plus.

Swap out `go` method with subject which is the convention.

Re-organize 'PUT update' to remove un-necessary context nesting.

DRY up repeated blocks to `add_maintainer` and `sign_in`

This is similar to the option in the Add Existing cluster form

Signed-off-by: Rémy Coutable <remy@rymai.me>

- Change find_cluster_platform_kubernetes to ignore environment argument
- Fix broken specs

CE Port of: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5047/