Adopt ConfigKit for pipeline loading

internal/config/notarius_test.go

@@ -107,6 +107,12 @@ notarius:
   enabled: true
   config_path: notarius/config.yml
   pipeline_id: dnd-session
+  outputs:
+    npc_registry:
+      lane_id: npc-registry
+      media_type: application/json
+      schema_id: notarius.dnd.npc_registry
+      schema_version: v1
 `
 	paths := make([]string, 2)
 	configs := make([]*PipelineConfig, 2)
@@ -151,7 +157,7 @@ func TestNotariusStrictYAML(t *testing.T) {
 			_, err := LoadPipeline(path)
 			want := "strict decode failed"
 			if tt.name == "duplicate reference selector" {
-				want = "duplicate YAML key"
+				want = "yaml.duplicate_key"
 			}
 			if err == nil || !strings.Contains(err.Error(), want) {
 				t.Fatalf("LoadPipeline() error = %v, want containing %q", err, want)