Display version tier to users
Summary
Dedicated issue for version display addition - spun out from #24618
Background
Feature access in GitLab.com is dependent on both subscription tier and version. In current state, it can be difficult for a logged-in user to know what their current tier/version is, as this is not easily displayed they have access to. Our docs list which tier+version is needed to have access to particular features, but there's no way for a user to make use of this info unless they are also an admin.
- Tier = Premium, Ultimate, Free, Dedicated
- Version = 15.4.0, 15.3.4, etc.