feat(SBC): Provision proto (#20452)

proto/sbc_provision.proto

@@ -0,0 +1,24 @@
+syntax = "proto3";
+
+// Provision a node via the serverless backfill controller.
+package serverless_backfill_controller;
+
+option optimize_for = SPEED;
+
+message ProvisionRequest {
+  // Leave it empty for future extension.
+}
+
+message ProvisionResponse {
+  string resource_group = 1;
+}
+
+service NodeGroupControllerService {
+  // Provision interacts with Kubernetes to provide a group of compute nodes.
+  // To avoid collision and simplify GC, it will generate the a name for node
+  // group identification.
+  // The RPC call will hold until all nodes haven been observed in the
+  // RisingWave's system catalog. Timeout may be applied over the call to
+  // cancel the request, and GC shall be taken care of by the service provider.
+  rpc Provision(ProvisionRequest) returns (ProvisionResponse);
+}