feat(control): add GetHostResources RPC

Add GetHostResources to the control service, reporting aggregate
hypervisor and host memory, CPU usage, and CPU/NUMA topology figures.

Author: azenla

protect/control/v1/control.proto

@@ -11,6 +11,7 @@ service ControlService {
   // Other control API snoops will be skipped from the responses.
   rpc SnoopControl(SnoopControlRequest) returns (stream SnoopControlReply);
   rpc GetHostCpuTopology(GetHostCpuTopologyRequest) returns (GetHostCpuTopologyReply);
+  rpc GetHostResources(GetHostResourcesRequest) returns (GetHostResourcesReply);
 
   rpc ListDevices(ListDevicesRequest) returns (ListDevicesReply);
 
@@ -719,6 +720,36 @@ message GetHostCpuTopologyReply {
   repeated HostCpuTopologyInfo cpus = 1;
 }
 
+// Requests aggregate memory, CPU, and topology figures for this machine.
+message GetHostResourcesRequest {}
+
+// Memory, CPU, and topology figures for this machine. `hypervisor_*` values
+// describe the whole machine as the hypervisor sees it; `host_*` values
+// describe the host (dom0) that Edera runs in.
+message GetHostResourcesReply {
+  // Memory figures are in bytes.
+  uint64 hypervisor_free_memory = 1;
+  uint64 hypervisor_used_memory = 2;
+  uint64 hypervisor_total_memory = 3;
+  uint64 host_free_memory = 4;
+  uint64 host_used_memory = 5;
+  uint64 host_total_memory = 6;
+
+  // CPU usage is the busy fraction as a percentage (0-100). Total time is the
+  // cumulative elapsed CPU time since boot, summed across all logical CPUs, in
+  // nanoseconds.
+  double hypervisor_cpu_usage = 7;
+  double host_cpu_usage = 8;
+  uint64 hypervisor_cpu_total_time = 9;
+  uint64 host_cpu_total_time = 10;
+
+  uint32 hypervisor_numa_nodes = 11;
+  uint32 hypervisor_cpu_cores = 12;
+  uint32 hypervisor_cpu_sockets = 13;
+  uint32 host_cpu_cores = 14;
+  uint32 host_cpu_sockets = 15;
+}
+
 // Sets the host power management policy. `scheduler` is a CPU frequency governor name,
 // applied to all host CPUs. `smt_awareness` toggles SMT-aware power management.
 message SetHostPowerManagementPolicyRequest {