增加“关闭时最小化到托盘”的设置 (#166)

添加托盘设置，调整主进程代码架构

src/main/rendererEvents/musicMeta.js

@@ -0,0 +1,6 @@
+const { mainOn } = require('../../common/ipc')
+const { setMeta } = require('../utils/musicMeta')
+
+mainOn('setMusicMeta', (event, { filePath, meta }) => {
+  setMeta(filePath, meta)
+})