Refactor design_management/components/toolbar/index.vue to use ApolloQuery component

Summary

Refactor ee/app/assets/javascripts/design_management/components/toolbar/index.vue to use <ApolloQuery> component.

Improvements

toolbar/index.vue uses Apollo query with options syntax. Refactoring it to use ApolloQuery component will help us split the logic more clearly between template and script parts and will also make our codebase more consistent

Risks

There are no significant risks on this refactoring

Involved components

• ee/app/assets/javascripts/design_management/components/toolbar/index.vue

Optional: Missing test coverage

• ee/spec/frontend/design_management/components/toolbar/index_spec.js