Enable Project Studio for members of groups with Experimental/Beta feature enabled

What does this MR do and why?

Enable Project Studio for members of groups with Experimental/Beta feature enabled

This defaults the Project Studio toggle to on for members of groups that have Experimental/Beta feature enabled. We also add the project_studio_early_access feature flag which will let us flip the switch when needed.

References

• https://gitlab.com/gitlab-org/gitlab/-/issues/577796+
• Project Studio Experimental/Beta Customer Rollout (#577994)

MR acceptance checklist

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Related to #577796