Migrate Feast UI to Use REST API Registry Server

[ntkathole]

Summary :

This is about proposing migrating the Feast UI to use the new REST API-based registry server as the primary data source instead of relying on the protobuf-serialized registry.

This migration will improve projects isolation, RBAC, production-grade deployments of Feast and will pave the way for a more flexible and secure UI architecture.

Goals can be :

• Fetch registry data via the REST API endpoints scoped by project.
• Eliminate dependency on serialized registry protos.
• Improve support for RBAC authenticated and authorized user access.
• Lay the foundation for future UI-driven create, update, and delete functionality.

This can be done by:

• Change FastAPI() https://github.com/feast-dev/feast/blob/master/sdk/python/feast/ui_server.py#L20 to use RestRegistryServer https://github.com/feast-dev/feast/blob/master/sdk/python/feast/api/registry/rest/rest_registry_server.py#L26
• Modify useLoadRegistry.ts and useLoadRelationshipsData.ts to use project name and registry rest-api server url
• Modify pages

[franciscojavierarceo]

I think this makes sense but we should make this configurable and default the behavior so that when a new user runs feast ui it expects the local registry (i.e., default to existing behavior).