Rename vue_component_helper to text_helper

What does this MR do?

CE Port: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28358

It doesn't make any sense why this file was named vue_component_helper and has been an often source of confusion to new team members. Let's rename it! 🚀

Does this MR meet the acceptance criteria?

Conformity

• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content