feat: add teams (#848)

## Description

Add support for teams which will allow users to collaborate on
documents.

Teams features allows users to:

- Create, manage and transfer teams
- Manage team members
- Manage team emails
- Manage a shared team inbox and documents

These changes do NOT include the following, which are planned for a
future release:

- Team templates
- Team API
- Search menu integration

## Testing Performed

- Added E2E tests for general team management
- Added E2E tests to validate document counts

## Checklist

- [X] I have tested these changes locally and they work as expected.
- [X] I have added/updated tests that prove the effectiveness of these
changes.
- [ ] I have updated the documentation to reflect these changes, if
applicable.
- [X] I have followed the project's coding style guidelines.

packages/lib/constants/billing.ts

@@ -0,0 +1,11 @@
+export enum STRIPE_CUSTOMER_TYPE {
+  INDIVIDUAL = 'individual',
+  TEAM = 'team',
+}
+
+export enum STRIPE_PLAN_TYPE {
+  TEAM = 'team',
+  COMMUNITY = 'community',
+}
+
+export const TEAM_BILLING_DOMAIN = 'billing.team.documenso.com';