[VSA parity] Expose Group-level VSA on the project-level

At this point, the VSA backend is able to load data for a given ProjectNamespace. We need to create a switch to enable the new endpoints and the group-level frontend for the paid users.

How:

When loading the VSA landing page, make and check for the license:

• If FOSS: render the old, legacy VSA view.
• If paid: render the group-level view with the group-level frontend.

Note: this seems a bit hacky, but this is a necessary step to expose the paid VSA on the project-level as soon as possible. At a later step, we'll add more permission checks on the UI to ensure that we can safely "downgrade" the feature for FOSS users.