CE Backport: Re-use MR tabs styles to Epic tabs

See merge request gitlab-org/gitlab-ce!26935

IDE fix MR detection from fork

See merge request gitlab-org/gitlab-ce!26986

**Why?**
Currently the IDE loads a merge request based on only the
`source_branch` name. This means it loads MR's from
forks that have the same branch name (not good).

- This required updating the BE API to accept `source_project_id`

Show error when namespace/svc account missing

Closes #54506

See merge request gitlab-org/gitlab-ce!26362

Fixing single string values in the 'include:' keyword of gitlab-ci.yml validations

See merge request gitlab-org/gitlab-ce!26998

This fix is a followup to !24098 which introduced a validation of the
`include:` keyword of a gitlab-ci configuration file when triggered
from /ci/lint API calls.

However, there was a test case missing: the case of a single string as
value. I have added a test case for that which shows that the code was
not validating it correctly.

This commit fixes that to allow all `include:` valid inputs.

Fix capitalization of a sentence in CONTRIBUTING.md

See merge request gitlab-org/gitlab-ce!27021

Backport Resizable container component for gl-charts

See merge request gitlab-org/gitlab-ce!26843

* Fix up graph resize logic if navbar is collapsed

Add snapshot

Clarify the Runner registration and authentication tokens

See merge request gitlab-org/gitlab-ce!26996

Merge branch '9217-warn-on-git-fetch-over-ssh-if-the-secondary-is-lagging-the-primary' into 'master'

Display console messages, if available

See merge request gitlab-org/gitlab-ce!26692

Resolve "Hide Kubernetes cluster warning if project has cluster related"

See merge request gitlab-org/gitlab-ce!26749

Fix and expand Gitaly FindCommit caching

See merge request gitlab-org/gitlab-ce!27018

Fix UI anchor links after docs refactor

See merge request gitlab-org/gitlab-ce!26890

Display cluster form validation error messages inline

Closes #57602

See merge request gitlab-org/gitlab-ce!26502

Replace comment by variable

See merge request gitlab-org/gitlab-ce!27007

Instead of having a comment describing what a specific value is,
better to have a variable with a meaningful name.

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26248 added
support for deduplicating FindCommit requests using Gitaly ref name
caching. However, not all endpoints were covered, and in one case the
Gitaly wrapper wasn't actually surrounding the serialization step. We
can safely cache ref names between FindCommit calls for #index and #show
endpoints for merge requests and pipelines. This can significantly
reduce the number of FindCommit requests.

Improve the Review Apps documentation by using gitlab-rails console

See merge request gitlab-org/gitlab-ce!27006

Update gitlab/eslint-config version

See merge request gitlab-org/gitlab-ce!27008

Drop legacy artifacts usage as there are no leftovers

See merge request gitlab-org/gitlab-ce!24294

Fix a KeyError in GitlabSchema

Closes #60057

See merge request gitlab-org/gitlab-ce!27011

Rename Workhorse terminal_specification to channel_specification

See merge request gitlab-org/gitlab-ce!26939

We're moving from using terminology related to terminals when
we refer to Websockets connections in Workhorse.
It's more appropiate a concept like channel.

Allow reactive caching to be used in services

See merge request gitlab-org/gitlab-ce!26839

Add support for defining a reactive_cache_worker_finder function
that will be used by the reactive_caching_worker to generate/initialize
the calling object. This allows reactive caching to work with Services
where the object cannot be obtained from DB but a new object can be
initialized.

Allow GraphQL Scalar-fields to be authorized

Closes #57831

See merge request gitlab-org/gitlab-ce!26338

Externalize strings in helpers

See merge request gitlab-org/gitlab-ce!26845

- Update qa selector
- Update PO file

Fix vue render error for IDE status bar

Closes #59995

See merge request gitlab-org/gitlab-ce!26979

Allow to sort wiki pages by date and title

See merge request gitlab-org/gitlab-ce!25365

- Add controls for sorting by title and date
- Execute Gitaly call which now accepts sorting params for wikis

Update GitLab Shell to v9.0.0

See merge request gitlab-org/gitlab-ce!27002