feat(runtime): add system resource metrics to /server_info endpoint

This PR adds CPU, memory, disk, and IO resource usage information to the /server_info endpoint response. The new metrics include:

CPU usage percentage for the current process
Memory usage (RSS, VMS, and percentage)
Disk usage (total, used, free space and usage percentage)
I/O statistics (read/write bytes and counts)

This information will help monitor the resource utilization of the runtime server.

To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:bfbbcce-nikolaik   --name openhands-app-bfbbcce   docker.all-hands.dev/all-hands-ai/openhands:bfbbcce

All-Hands-AI / OpenHands

feat(runtime): add system resource metrics to /server_info endpoint #5207