Extracts the API implementation to a package so we can
potentially reuse it across different applications in the
event that we move off using a Next.js API route.
Additionally tidies up the tokens page and form to be more simplified.
## Description
Previously we assumed that there can only be 1 subscription per user.
However, that will soon no longer the case with the introduction of the
Teams subscription.
This PR will apply the required migrations to support multiple
subscriptions.
## Changes Made
- Updated the Prisma schema to allow for multiple `Subscriptions` per
`User`
- Added a Stripe `customerId` field to the `User` model
- Updated relevant billing sections to support multiple subscriptions
## Testing Performed
- Tested running the Prisma migration on a demo database created on the
main branch
Will require a lot of additional testing.
## Checklist
- [ ] I have tested these changes locally and they work as expected.
- [ ] I have added/updated tests that prove the effectiveness of these
changes.
- [X] I have followed the project's coding style guidelines.
## Additional Notes
Added the following custom SQL statement to the migration:
> DELETE FROM "Subscription" WHERE "planId" IS NULL OR "priceId" IS
NULL;
Prior to deployment this will require changes to Stripe products:
- Adding `type` meta attribute
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Co-authored-by: Lucas Smith <me@lucasjamessmith.me>
