SetupDevices RPC and Device messages for DRA/CDI GPU passthrough

Need
sysbox-runc and sysbox-mgr must coordinate which host device nodes belong to a container as part of the DRA/CDI GPU passthrough feature.
Today the IPC interface has no message to carry that device set, so the feature cannot be plumbed end-to-end.

Proposal
Add a SetupDevices gRPC RPC to the sysbox-mgr IPC proto, plus supporting Device / request / response messages, wired through grpcServer.go (the ServerCallbacks field + handler) and grpcClient.go (client wrapper).
The regenerated sysboxMgrProtobuf.pb.go is gitignored and rebuilt by make.

Benefits
Gives sysbox-mgr a clean, typed channel to tell sysbox-runc which device nodes (e.g. NVIDIA MIG capability nodes) to set up for a container, enabling GPU/MIG passthrough for system containers driven by DRA/CDI.

Part of a 3-repo feature (see sysbox-mgr and sysbox-runc PRs).

Start with the IPC proto and inspect existing RPC patterns in grpcServer.go and grpcClient.go. Add the SetupDevices RPC with its Device, request, and response messages, wire the ServerCallbacks handler and client wrapper, then run make to regenerate sysboxMgrProtobuf.pb.go and verify the interface builds.