Show group sidebar while creating a new subgroup or project

app/assets/javascripts/pages/groups/new/components/app.vue

app/assets/javascripts/pages/groups/new/index.js

app/assets/javascripts/projects/new/components/app.vue

app/assets/javascripts/projects/new/index.js

...vascripts/vue_shared/new_namespace/new_namespace_page.vue

app/controllers/groups_controller.rb

app/controllers/projects_controller.rb

app/helpers/groups_helper.rb

app/views/groups/_new_group_fields.html.haml

app/views/groups/new.html.haml

app/views/layouts/dashboard.html.haml

app/views/layouts/nav/sidebar/_group.html.haml

app/views/projects/_new_project_fields.html.haml

app/views/projects/new.html.haml

ee/app/helpers/ee/groups_helper.rb

...ntend/vue_shared/new_namespace/new_namespace_page_spec.js

lib/sidebars/groups/menus/scope_menu.rb

locale/gitlab.pot

spec/features/groups/new_group_page_spec.rb

spec/features/projects/new_project_spec.rb