This commit introduces gRPC-based log streaming between the VM runner (`solstice-runner`) and orchestrator. Key updates include:
- Implemented gRPC server in the orchestrator for receiving and processing runner logs.
- Added log streaming and job result reporting in the `solstice-runner` client.
- Defined `runner.proto` with messages (`LogItem`, `JobEnd`) and the `Runner` service.
- Updated orchestrator to accept gRPC settings and start the server.
- Modified cloud-init user data to include gRPC endpoint and request ID for runners.
- Enhanced message queue logic to handle job results via `publish_job_result`.
- Configured `Cross.toml` for cross-compilation of the runner.
This commit updates the `Scheduler` to support cooperative shutdown using `Notify`, allowing graceful termination of tasks and cleanup of placeholder VMs. Additionally, the AMQP consumer is enhanced with an explicit shutdown mechanism, ensuring proper resource cleanup, including closing channels and connections.
This commit introduces the ability to configure placeholder VM run time via an environment variable (`VM_PLACEHOLDER_RUN_SECS`) and updates the `Scheduler` to accept this duration. Additionally, it implements a graceful shutdown mechanism for the orchestrator, allowing cooperative shutdown of consumers and cleanup of resources.
