feat(grpc): introduce Status and ServerStatus types

[sauravzg]

Introduces the foundational Status and ServerStatus types for gRPC status handling.

• Status: Represents a standard gRPC status with a code and message.
• ServerStatus: A wrapper around Status designed to prevent accidental leakage of sensitive server errors to the client. This type distinction ensures that handlers must explicitly convert to Status, encouraging a conscious decision about what information is exposed.
• StatusCode: Enum representing standard gRPC status codes.

This implementation provides the necessary types to unblock server-side API development without relying on a heavy tonic::Status. This is not meant to be an intermediate or final Status implementation but serves as a way to implement functional requirements while we design the final Status.

[darth-raijin]

I left one suggestion on the tests about avoiding duplication of the "ok" message by assigning it to a variable and reusing it in the assertions. It should make the test a bit less brittle if the message ever changes.

[darth-raijin]

Right now the "ok" message is duplicated in both the constructor call and the assertion.

To make the test less brittle, I’d suggest assigning the message to a variable and reusing it, e.g.:

let message = "ok";
let status = Status::new(StatusCode::Ok, message);

assert_eq!(status.code(), StatusCode::Ok);
assert_eq!(status.message(), message);