OAuth at a per-user basis

Currently, OAuth access to Front is granted at a company level (and only accessible for company admins). While this is useful for connecting the whole account to an external service, sometimes we want to grant OAuth at a per-teammate level.
Use cases could be;
- Allowing individual teammates to connect their Front individual mailboxes to external services via OAuth
- Providing information to teammates from external services based on the context of what their OAuth Access Token allows them to access
- Offering a Log In With Front sign-in option(!)