json: enable WithName logging

The name added to a logger via WithName only gets printed when a key is
chosen. "logger" is used as in the zap examples.

This becomes relevant once we support contextual logging. When logging through
klog the name is always empty.

staging/src/k8s.io/component-base/logs/json/json.go

@@ -43,6 +43,7 @@ func NewJSONLogger(infoStream, errorStream zapcore.WriteSyncer, encoderConfig *z
 		encoderConfig = &zapcore.EncoderConfig{
 			MessageKey:     "msg",
 			CallerKey:      "caller",
+			NameKey:        "logger",
 			TimeKey:        "ts",
 			EncodeTime:     epochMillisTimeEncoder,
 			EncodeDuration: zapcore.StringDurationEncoder,

staging/src/k8s.io/component-base/logs/json/json_test.go

@@ -61,10 +61,9 @@ func TestZapLoggerInfo(t *testing.T) {
 			keysValues: []interface{}{"duration", time.Duration(5 * time.Second)},
 		},
 		{
-			msg:   "test for WithName",
-			names: []string{"hello", "world"},
-			// TODO: log names
-			format: "{\"ts\":%f,\"caller\":\"json/json_test.go:%d\",\"msg\":\"test for WithName\",\"v\":0}\n",
+			msg:    "test for WithName",
+			names:  []string{"hello", "world"},
+			format: "{\"ts\":%f,\"logger\":\"hello.world\",\"caller\":\"json/json_test.go:%d\",\"msg\":\"test for WithName\",\"v\":0}\n",
 		},
 	}