Create merge request from email

Closes #32878

See merge request gitlab-org/gitlab-ce!13817

Small Gitlab::Git fixes for Gitaly

See merge request gitlab-org/gitlab-ce!15675

Second iteration of Move Kubernetes from service to Cluster page

Closes #35616 and #39826

See merge request gitlab-org/gitlab-ce!14805

Cache the forks in a namespace in the RequestStore

Closes #40625

See merge request gitlab-org/gitlab-ce!15663

Backport Extract epic nav into separate partial for easier CE => EE

See merge request gitlab-org/gitlab-ce!15655

[CE] Move git operations for squash and rebase into Gitlab::Git

See merge request gitlab-org/gitlab-ce!15673

Clarify the docs review process and mention the supported repos

See merge request gitlab-org/gitlab-ce!15573

Backport EE changes from refactor sidebar weight block Vue and move to Issue Boards

See merge request gitlab-org/gitlab-ce!15706

remove ambiguity about which resource type to be using for new sessions

Closes #39367

See merge request gitlab-org/gitlab-ce!15726

Prevent job link form rendering when user does not have permissions

Closes #40739

See merge request gitlab-org/gitlab-ce!15723

* new merge request can be created by sending an email to the specific
email address (similar to creating issues by email)
* for the first iteration, source branch must be specified in the mail
subject, other merge request parameters can not be set yet
* user should enable "Receive notifications about your own activity" in
user settings to receive a notification about created merge request

Part of #32878

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3566

Migrate Gitlab::Git::Repository#cherry_pick to Gitaly

Closes gitaly#737

See merge request gitlab-org/gitlab-ce!15517

The former is in Ruby's core lib, so is more flexible.

Use custom User-Agent header in GCP Client requests

Closes #40583

See merge request gitlab-org/gitlab-ce!15705

Reduce pipeline chain life span to minimize side effects

See merge request gitlab-org/gitlab-ce!15716

Closes gitaly#737

Import axios utils in commons chunks

See merge request gitlab-org/gitlab-ce!15721

On the `show` of a project that is part of a fork network. We check if
the user already created a fork of this project in their personal
namespace.

We do this in several places, so caching the result of this query in
the request store prevents us from repeating it.