Move labels code to ~/labels

...uable_bulk_update_sidebar/issuable_bulk_update_sidebar.js

app/assets/javascripts/labels/create_label.js

app/assets/javascripts/labels/delete_label_modal.js

app/assets/javascripts/labels/group_label_subscription.js

app/assets/javascripts/labels/init_labels.js

app/assets/javascripts/labels/label_manager.js

app/assets/javascripts/labels/labels.js

app/assets/javascripts/labels/labels_select.js

app/assets/javascripts/labels/project_label_subscription.js

app/assets/javascripts/pages/admin/labels/edit/index.js

app/assets/javascripts/pages/admin/labels/new/index.js

app/assets/javascripts/pages/groups/labels/edit/index.js

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

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

app/assets/javascripts/pages/projects/issues/form.js

app/assets/javascripts/pages/projects/labels/edit/index.js

app/assets/javascripts/pages/projects/labels/index/index.js

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

...ripts/pages/projects/merge_requests/init_merge_request.js

ee/app/assets/javascripts/labels/labels.js