Create a wrapper for PolicyCRUD that currently communicates with the Auth service.

[arvindh123]

At present, service access the SpiceDB via Auth gRPC client.

Idea here is that , service should use PolicyCRUD wrapper , service should use function in PolicyCRUD wrapper for all it operation related to Policy.

Service should not have gRPC client connection, service should not know the backend communication,
Instead PolicyCRUD wrapper should take care of communication with Auth Service.