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/

Fix problem with spec that showed up in EE merge

See merge request gitlab-org/gitlab-ce!22675

docs: Add deprecation notice for renamed licensed feature

See merge request gitlab-org/gitlab-ce!22575

Added a note about machine types

See merge request gitlab-org/gitlab-ce!22572

Update gitlab-ui to 1.9.0

See merge request gitlab-org/gitlab-ce!22632

Remove mousetrap-rails gem

Closes #53270

See merge request gitlab-org/gitlab-ce!22647

Make new merge request URL more friendly when pushing code

Closes #53012

See merge request gitlab-org/gitlab-ce!22526

Add e2e test to push using a private token

See merge request gitlab-org/gitlab-ce!22628

Update moment to 2.22.2

Closes #53273

See merge request gitlab-org/gitlab-ce!22648

Update GitLab Pages to v1.3.0

See merge request gitlab-org/gitlab-ce!22666

Replace deprecated uniq on a Relation with distinct

See merge request gitlab-org/gitlab-ce!22625

Rename 'sast_container' licensed feature

See merge request gitlab-org/gitlab-ce!22662

Upgrade whitequark/parser to 2.5.3.0

See merge request gitlab-org/gitlab-ce!22652

Delete job_spec.js

See merge request gitlab-org/gitlab-ce!22664

Tests pushing over HTTP(S) using a personal access token

Truncate milestone title on collapsed sidebar

See merge request gitlab-org/gitlab-ce!22624

Fix broken "Show whitespace changes" button on MR "Changes" tab

Closes #52122

See merge request gitlab-org/gitlab-ce!22539

Remove all tables from Pipeline page when there is no job for the Pipeline

Closes #45669

See merge request gitlab-org/gitlab-ce!18540

Extract ee specific lines for issues and mr controllers

See merge request gitlab-org/gitlab-ce!22569

Fix open-ended params for api_json.log

Closes #53155

See merge request gitlab-org/gitlab-ce!22623

adds warning against Postgres across NFS

See merge request gitlab-org/gitlab-ce!22278

CE Backport: Show actual Milestone dates within tooltips for Milestones in Epics sidebar

See merge request gitlab-org/gitlab-ce!22653

post merge pipeline and environments status

Closes #47799

See merge request gitlab-org/gitlab-ce!22292

Clarify last board navigation documentation

Closes gitlab-ee#7760

See merge request gitlab-org/gitlab-ce!22618

`Create a new tag` json Missing double quotes

See merge request gitlab-org/gitlab-ce!22614

Models and migrations for group level clusters

See merge request gitlab-org/gitlab-ce!22307

Add None/Any options for assignee in search bar

Closes #52383

See merge request gitlab-org/gitlab-ce!22599

Backport CE route changes for Ops Dashboard in EE

See merge request gitlab-org/gitlab-ce!22640