Unclear error message when testing in simulation

[kbamponsem]

Description

This PR fixes ambiguous error message when executing integration tests in software (SW) mode.

Describe your changes in detail

• It adds a new check code for FAILED_PRECONDITION to the lists of GRPC error checks on the client side.

  def check_rpc_exception(rpc_error):
  if rpc_error.code() == grpc.StatusCode.CANCELLED:
      return f"Cancelled GRPC call: code={rpc_error.code()} message={rpc_error.details()}"
  
  elif rpc_error.code() == grpc.StatusCode.UNAVAILABLE:
      return f"Failed to connect to GRPC server: code={rpc_error.code()} message={rpc_error.details()}"
  
  elif rpc_error.code() == grpc.StatusCode.UNIMPLEMENTED:
      return f"Incompatible client/server versions, code={rpc_error.code()} message={rpc_error.details()}"
  
  elif rpc_error.code() == grpc.StatusCode.FAILED_PRECONDITION:
      return f"Attestation is not available. Running in Simulation Mode, code={rpc_error.code()} message={rpc_error.details()}"
  else:
      return (
          f"Received RPC error: code={rpc_error.code()} message={rpc_error.details()}"
      )

• Also, on the server-side in Rust, the status code has been changed to match the client's check.

if cfg!(SGX_MODE = "SW") {
            return Err(Status::failed_precondition(
                "Attestation is not available. Running in Simulation Mode",
            ));
        }

Type of change

The types of changes must be deduced from the labels of the related issues. Please consider providing these further details.

• [ ] This change requires a documentation update
• [ ] This change affects the client
• [ ] This change affects the server
• [ ] This change affects the API
• [ ] This change only concerns the documentation

How Has This Been Tested?

It was tested in a simulation environment and the proper error message was witnessed.

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings
• [ ] I have updated the documentation according to my changes