Add runtime config api.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/api/runtimeoptions/v1/api.proto

@@ -0,0 +1,22 @@
+// To regenerate api.pb.go run `make proto`
+syntax = "proto3";
+
+package cri.runtimeoptions.v1;
+
+import "github.com/gogo/protobuf/gogoproto/gogo.proto";
+
+option (gogoproto.goproto_stringer_all) = false;
+option (gogoproto.stringer_all) =  true;
+option (gogoproto.goproto_getters_all) = true;
+option (gogoproto.marshaler_all) = true;
+option (gogoproto.sizer_all) = true;
+option (gogoproto.unmarshaler_all) = true;
+option (gogoproto.goproto_unrecognized_all) = false;
+
+message Options {
+  // TypeUrl specifies the type of the content inside the config file.
+  string type_url = 1;
+  // ConfigPath specifies the filesystem location of the config file
+  // used by the runtime.
+  string config_path = 2;
+}