Merge master into feature branch, fix conflicts

.gitattributes

.gitlab/CODEOWNERS

.gitlab/ci/docs.gitlab-ci.yml

.gitlab/ci/frontend.gitlab-ci.yml

.gitlab/ci/global.gitlab-ci.yml

.gitlab/ci/pages.gitlab-ci.yml

.gitlab/ci/qa.gitlab-ci.yml

.gitlab/ci/rails.gitlab-ci.yml

.gitlab/ci/review.gitlab-ci.yml

.gitlab/issue_templates/Problem_Validation.md

.gitlab/issue_templates/Security developer workflow.md

.haml-lint_todo.yml

.rubocop.yml

.rubocop_todo.yml

Dangerfile

GITALY_SERVER_VERSION

GITLAB_SHELL_VERSION

Gemfile

Gemfile.lock

app/assets/javascripts/api.js