Show pre-enforcement storage banner on project page

What does this MR do and why?

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/350632

This enables the project pages to show the pre-enforcement storage banner as the requirement in the issue states

Screenshots or screen recordings

No UI changes at this point, so just showing the banner as is:

How to set up and validate locally

1. To make the banner appear:
   1. Either enable this FF: Feature.enable(:namespace_storage_limit_bypass_date_check)
   2. Or replace nil with Date.current in the storage_enforcement_date method
2. Go to a free group's project page
3. Make sure the banner in the screenshot is showing

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.