Feature Request: Future Authentik Enhancements

# Feature Request: Future Authentik Enhancements

## Custom Permission Attributes
Roles today only serve as buckets of built-in global and object permissions; there are no dynamic attribute fields on roles like there are on Users and Groups.
- Enable defining **custom permissions** on roles to assign application-specific permission sets directly in Authentik.

## User-Scoped API Tokens via OAuth2
Extend the Authorization Code and Hybrid flows (or implement an RFC 8693 Token Exchange) so that login returns a `goauthentik.io/api`-scoped access token alongside the ID Token.
- Allow direct Management API calls using the user’s OAuth2 access token without extra scope configuration.

## gRPC API Endpoints
Provide a first-class gRPC interface (with Protobuf definitions and HTTP/2 multiplexing) to support low-latency, binary-serialized service-to-service calls alongside the existing REST/JSON API.
- Offer generated gRPC client libraries for streamlined microservice integration.