Add create sub-command setup

.gitlab/ci/test-on-cng/main.gitlab-ci.yml

gems/gitlab-cng/lib/gitlab/cng/cli.rb

gems/gitlab-cng/lib/gitlab/cng/commands/_command.rb

gems/gitlab-cng/lib/gitlab/cng/commands/create.rb

gems/gitlab-cng/lib/gitlab/cng/commands/doctor.rb

gems/gitlab-cng/lib/gitlab/cng/commands/version.rb

gems/gitlab-cng/lib/gitlab/cng/lib/helpers/output.rb

gems/gitlab-cng/lib/gitlab/cng/lib/helpers/shell.rb

gems/gitlab-cng/lib/gitlab/cng/lib/helpers/spinner.rb

gems/gitlab-cng/lib/gitlab/cng/lib/helpers/thor.rb

gems/gitlab-cng/lib/gitlab/cng/lib/kind/cluster.rb

gems/gitlab-cng/lib/gitlab/cng/lib/kind/configs.rb

gems/gitlab-cng/spec/command_helper.rb

gems/gitlab-cng/spec/integration/cng_spec.rb

gems/gitlab-cng/spec/integration/gitlab/cng/cli_spec.rb

gems/gitlab-cng/spec/spec_helper.rb

gems/gitlab-cng/spec/unit/gitlab/cng/commands/create_spec.rb

gems/gitlab-cng/spec/unit/gitlab/cng/commands/doctor_spec.rb

.../gitlab-cng/spec/unit/gitlab/cng/commands/version_spec.rb

gems/gitlab-cng/spec/unit/gitlab/cng/helpers/spinner_spec.rb