Migrate scala control messages to protobuf

[shengquan-ni]

This PR migrates all Scala control messages and their corresponding handlers to use gRPC.

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Main Changes (For both Scala and Python Engine)

1. Rewrote AsyncRPCServer and AsyncRPCClient

   • Adjusted both to fit into the generated gRPC interface, while keeping RPCs sent and received through actor messages.

2. Centralized RPC Definitions

   • All RPC messages and method definitions are now located in:

     src/main/protobuf/edu/uci/ics/amber/engine/architecture/rpc
     

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Steps to Create New RPCs

1. Create a request proto message in controlcommands.proto with all necessary inputs.
2. Create a response proto message in controlreturns.proto.
3. Define the RPC:
   • For controller-handled RPCs, add the definition to controllerservice.proto.
   • For worker-handled RPCs, add it to workerservice.proto.
4. Generate Scala code by running protocGenerate in the SBT shell.
5. Generate Python code by running ./scripts/python-proto-gen.sh from core folder.
6. Implement the RPC handler:
   • Scala Engine: in either ControllerAsyncRPCHandlerInitializer or WorkerAsyncRPCHandlerInitializer, and move it to the promisehandlers folder for better organization.
   • Python Engine: create a new handler under python/core/architecture/handlers/control and override corresponding async method for the new rpc defined in worker service.

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Changes in Sending RPCs (Scala Engine)

Example: Using the StartWorkflow RPC, which is handled by the controller.

• Before this PR:

  send(StartWorkflow(), CONTROLLER).map { ret =>
    // handle the return value
  }

• After this PR:

  controllerInterface.startWorkflow(EmptyRequest(), mkContext(CONTROLLER)).map { resp =>
      // handle the response
  }

[Yicong-Huang]

LGTM! Had some tests locally and left some comments in code.

[Yicong-Huang]

LGTM! Had some tests locally and left some comments in code.