Desktop (macOS): Add macOS "Close Window" menu item and add name to Quit menu (#1434)

* Add Close Window to macOS file menu

* Add Joplin to Quit menu item

On macOS the application name appears usually within the Quit menu item.

* Use performClose: selector for Close Window

* Revert Quit with name and add Quit string to translations

* Move Quit translation to joplin.pot

* Remove Quit string

ElectronClient/app/app.js

@@ -589,6 +589,14 @@ class Application extends BaseApplication {
 				newTodoItem,
 				newNotebookItem, {
 					type: 'separator',
+					visible: shim.isMac() ? true : false
+				}, {
+					label: _('Close Window'),
+					platforms: ['darwin'],
+					accelerator: 'Command+W',
+					selector: 'performClose:',
+				}, {
+					type: 'separator',
 				}, {
 					label: _('Import'),
 					submenu: importItems,