[Feature] Integrate Apps with Nesis

[mawandm]

Description Allow other apps to integrate with Nesis.

Detail This feature enables Nesis to be used within the enterprise by integrating with existing enterprise applications. This allows application developers to build applications that leverage generative AI applying it to internal enterprise applications and take advantage of Nesis' data ingestion, security and privacy model.

Acceptance Criteria

1. An app can be registered and given a unique applications token. This is used to authenticate the app on every API request.
2. An app can have a role attached to it. When this is the case, all API requests permissions are validated for the actions they are attempting to perform.
3. When an API request is made by the app and an X-Nesis-Request-UserKey is present in the header, then the request's action is validated against the roles attached to the user (whose user_id is the value of the header key X-Nesis-Request-UserKey).
4. An app token can have an expiry.