feat(plugin): add test.demo v1.0.0 (#4)

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Author: github-actions[bot]

plugins/test.demo.js

@@ -0,0 +1,10 @@
+/**
+ * @name        测试插件
+ * @id          test.demo
+ * @version     1.0.0
+ * @type        control
+ * @apiLevel    2
+ * @author      tester
+ * @description 测试用控制插件
+ */
+splayer.register({ events: ["trackChange"] });