Drop support for Go 1.9 in GitLab 11.4

Closes #51982

See merge request gitlab-org/gitlab-ce!22324

Updates the check for started in job header

See merge request gitlab-org/gitlab-ce!22329

Add stage name in job.json response

Closes #52618

See merge request gitlab-org/gitlab-ce!22317

The function that was checking if the job was started or not
was expecting a boolean, however it was receiving a null.
During the refactor the condition was changed, causing the function
to break with null

This commit fixes the check

Fix the event API docs

Closes #52512

See merge request gitlab-org/gitlab-ce!22320

Backport CE changes for Ops Dashboard in EE

See merge request gitlab-org/gitlab-ce!22136

Updates gitlab-svg dependency

See merge request gitlab-org/gitlab-ce!22299

Update GitLab Pages to v1.2.1

See merge request gitlab-org/gitlab-ce!22318

Hide job sidebar on mobile

Closes #52608

See merge request gitlab-org/gitlab-ce!22314

Resolve "Make file browser hidden by default for mobile screens" and improve layout in small screens too

Closes #52361

See merge request gitlab-org/gitlab-ce!22273

This commit adds back `js-` classes needed to
automatically collapse the sidebar on resize.

Specification change: Fix asciidoctor block context.

See merge request gitlab-org/gitlab-ce!22280

Fix broken file name navigation on MRs

Closes #50185

See merge request gitlab-org/gitlab-ce!22109

4. enable jasmine/prefer-jasmine-matcher

See merge request gitlab-org/gitlab-ce!22236

1. enable jasmine/new-line-between-declarations

See merge request gitlab-org/gitlab-ce!22230

Fix erased block not being rendered when job was erased

Closes #52570

See merge request gitlab-org/gitlab-ce!22294

Update copy to clipboard button data for application secret

Closes #52572

See merge request gitlab-org/gitlab-ce!22268

Fix project deletion when there is a export available

Closes #52362

See merge request gitlab-org/gitlab-ce!22276

Support pushing of feature flags to the frontend

Closes gitlab-org/release/framework#17

See merge request gitlab-org/gitlab-ce!22197

Adds `.json` to the end of pipelines endpoint

Closes #52472

See merge request gitlab-org/gitlab-ce!22293

Stuck block URL links to runners settings

Closes #52519

See merge request gitlab-org/gitlab-ce!22286

This adds a method to Gitlab::GonHelper called
`push_frontend_feature_flag`. This method can be used to easily expose
the state of a feature flag to Javascript code. For example, using this
method we may write the following controller code:

    before_action do
      push_frontend_feature_flag(:vim_bindings)
    end

    def index
      # ...
    end

    def edit
      # ...
    end

In Javascript we can then check the state of the flag as follows:

    if ( gon.features.vimBindings ) {
      // ...
    }

Fixes https://gitlab.com/gitlab-org/release/framework/issues/17

Enable even more frozen string in lib/**/*.rb

See merge request gitlab-org/gitlab-ce!22206

Feature improved branch filter sorting

See merge request gitlab-org/gitlab-ce!22166

Instance SAML SSO e2e test

Closes gitlab-qa#257

See merge request gitlab-org/gitlab-ce!22271

Add new sort option "most_stars" to "Group > Children" pages

See merge request gitlab-org/gitlab-ce!22121