`Changes to free tier public projects` alert is shown to all users

Summary

The Changes to free tier public projects alert is shown to users that are not a member of the group or project. It probably makes sense to only show this banner to users that can admin the the group or project.

Steps to reproduce

Visit a group or project you are not a member of on GitLab.com. https://gitlab.com/inkscape/inkscape

Example Project

https://gitlab.com/inkscape/inkscape

What is the current bug behavior?

Changes to free tier public projects alert is shown to users that are not a member of the group or project.

What is the expected correct behavior?

Changes to free tier public projects should only be shown to users that can admin the group or project.

Relevant logs and/or screenshots

Possible fixes

Add permissions check to ee/app/helpers/ee/namespaces_helper.rb#L64