insights: modal to announce GA

Created by: Joelkw

Note there is a dependency on https://github.com/sourcegraph/customer/issues/655

We need to update our beta modal copy to announce our GA!

This is part of RFC 566

• It should show to all users the first time they visit the product on 3.37 and after Feb 24th, and they have to acknowledge/accept it
• We can keep the graphic the same
• We need to update the text to – https://docs.google.com/document/d/1j-E_5Q4vat7koWHiKVVIiD3Iy4W5pSr7yMlXEIn78yc/edit

We need to set this explicitly tied to 3.37. If a user has not accepted but is on 3.38 or higher, we don't want to show it because they won't still have access – things will be no longer free after that. This can happen if someone is on an old instance that is quickly upgraded from 3.35 to 3.39 before they revisit Insights. In that case, we should never fire this modal.

So, the only conditions you (per user) see this modal are all of the below, AND-ed:

• You are on Sourcegraph 3.37.x
• It is after Feb 24, 2022
• You have not already accepted it
• You haven't purchased it (no code-insights license tag)

The general logic of taking folks back to the homepage if don't accept, etc., can all be reused from the beta modal.