feat: add enterprise billing (#939)

## Description

Add support for enterprise billing plans.

Enterprise billing plans by default get access to everything early
adopters do:
- Unlimited teams
- Unlimited documents

They will also get additional features in the future.

## Notes

Pending webhook updates to support enterprise onboarding.
Rolled back env changes `NEXT_PUBLIC_PROJECT` since it doesn't seem to
work.

packages/ee/server-only/stripe/get-enterprise-plan-prices.ts

@@ -0,0 +1,13 @@
+import { STRIPE_PLAN_TYPE } from '@documenso/lib/constants/billing';
+
+import { getPricesByPlan } from './get-prices-by-plan';
+
+export const getEnterprisePlanPrices = async () => {
+  return await getPricesByPlan(STRIPE_PLAN_TYPE.ENTERPRISE);
+};
+
+export const getEnterprisePlanPriceIds = async () => {
+  const prices = await getEnterprisePlanPrices();
+
+  return prices.map((price) => price.id);
+};