[MM-22102] upgrade to electron 7 (#1268)

* fix errors

* upgrade to electron 7

* getsavepath is deprecated

* fix typo

* disable messaging from 'null'

* replace getname to its property

* deprecated zoomlevel

* deprecated setbadgecount

* isdarkmode deprecated

* it's a property, not a function

* fix error message

* fix test

* fix test on linux

src/main/menus/app.js

@@ -12,7 +12,7 @@ function createTemplate(mainWindow, config, isDev) {
     type: 'separator',
   };
 
-  const appName = app.getName();
+  const appName = app.name;
   const firstMenuName = (process.platform === 'darwin') ? appName : 'File';
   const template = [];