Add feature flag for using go-git in Gitaly

See merge request gitlab-org/gitlab-ce!19305

Show a more helpful error for import status

Closes #47365

See merge request gitlab-org/gitlab-ce!19467

Docs: add the documentation guidelines into its own dir

See merge request gitlab-org/gitlab-ce!19323

Rails 5 fix glob spec

Closes #47376

See merge request gitlab-org/gitlab-ce!19469

Adjust monitoring graphs to support widgets in EE

See merge request gitlab-org/gitlab-ce!18062

Use Github repo visibility during import while respecting restricted visibility levels

Closes #47189

See merge request gitlab-org/gitlab-ce!19450

Add Avatar API

Closes #45821

See merge request gitlab-org/gitlab-ce!19121

Rename Secret variables -> variables

See merge request gitlab-org/gitlab-ce!19309

GraphQL setup: Basic Project and Merge request endpoint

Closes #34754

See merge request gitlab-org/gitlab-ce!19008

Resolve "Upgrade from source documentation - golang version required"

Closes #47204

See merge request gitlab-org/gitlab-ce!19434

QA Tests for Auto DevOps

See merge request gitlab-org/gitlab-ce!19200

Gitaly itself hold very little state, other than the data on disk. This
limits the interfaces to set feature flags. Gitaly now has the ability
to interpret the request metadata to check for feature flags.
https://gitlab.com/gitlab-org/gitaly/merge_requests/704
This allows clients control on the Gitaly server, and given that Rails
has an internal chatops interface to set these values this was chosen as
solution.

Known limitation right now, is that this package doesn't support the opt
out that other Gitaly features do.

Show job logs in web IDE

Closes #46245

See merge request gitlab-org/gitlab-ce!19279

Migrate jobs in object_storage_upload queue

Closes gitlab-ee#4811

See merge request gitlab-org/gitlab-ce!19180

There's no need to add a redundant message to the errors if the
model is invalid. This cleans up the message as well for the importer.

- All definitions have been replaced by classes:
  http://graphql-ruby.org/schema/class_based_api.html
- Authorization & Presentation have been refactored to work in the
  class based system
- Loaders have been replaced by resolvers
- Times are now coersed as ISO 8601

Bump grape-path-helpers to 1.0.2 to get updated Rake task naming

See merge request gitlab-org/gitlab-ce!19474

Importing a project from GitHub for a project namespace that already exists
would show an unhelpful error, "An error occurred while importing project."
We now add the base message from Projects::CreateService when this fails.

Closes #47365

Merge branch '47196-actionview-missingtemplate-missing-template-projects-merge_requests-invalid-projects-merge_requests-application-invalid-pr' into 'master'

Resolve "ActionView::MissingTemplate: Missing template projects/merge_requests/invalid, projects/merge_requests/application/invalid, pr..."

Closes #47196

See merge request gitlab-org/gitlab-ce!19356

Resolve "Manual job's triggered by datetime is wrong"

Closes #46858

See merge request gitlab-org/gitlab-ce!19438

Add development documentation on how to generate a list of routes

Resolve "POST api/v4/projects/:id/pipeline should accept variables"

Closes #25045

See merge request gitlab-org/gitlab-ce!19124

Rails 5 fix unknown keywords: changes, key_id, project, gl_repository, action,…

Closes #47368

See merge request gitlab-org/gitlab-ce!19466

Resolve "[Rails5] Fix specs with "text/plain; charset=utf-8""

Closes #47378

See merge request gitlab-org/gitlab-ce!19462

moved values to constants