#9336 Python: Improve error reporting from gRPC to client

Surface gRPC failure context to Python script authors instead of
silently returning sentinel values or raising bare gRPC errors.

- RipsError now carries code/details/location and a from_rpc_error()
  helper. Existing single-arg construction stays valid.
- Stop swallowing grpc.RpcError in case.__grid_count for non-NOT_FOUND
  failures and in instance._check_connection_and_version, so the
  underlying status is propagated.
- pdmobject add_method decorator and _call_pdm_method_* attach
  code/details to the raised RipsError; existing message text is
  preserved so pytest match=... assertions keep working.
- Instance.start_heartbeat / stop_heartbeat / check_alive provide an
  opt-in background ping that flips a sticky lost-connection flag and
  raises a readable RipsError from check_alive() if the server dies.
- Server side: GetPdmObject in RiaGrpcAppService, RiaGrpcCaseService
  and RiaGrpcProjectService no longer return Status::OK with an empty
  reply when the underlying object is missing; they return NOT_FOUND
  / INTERNAL with a descriptive message. Other RiaGrpc*Service files
  audited and already return non-OK with text on error paths.

GrpcInterface/RiaGrpcCaseService.cpp

@@ -176,8 +176,9 @@ grpc::Status RiaGrpcCaseService::GetPdmObject( grpc::ServerContext*     context,
     if ( rimCase )
     {
         copyPdmObjectFromCafToRips( rimCase, reply );
+        return grpc::Status::OK;
     }
-    return grpc::Status::OK;
+    return grpc::Status( grpc::NOT_FOUND, "Case not found" );
 }
 
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