Raise the desktop window when a notification is clicked [WPB-28731]

[thisisamir98]

WPB-28731 [Web] Send a system notification 10 minutes before a meeting starts

Summary

• A notification click now shows the desktop window even when Wire is already open behind another app.
• On macOS the app is activated as well, because focusing the window alone leaves it in the background.
• Each signed-in account still gets its own notification. This only changes what a click does.

Test plan

• With Wire open behind another app, click a meeting reminder and confirm Wire comes to the front.
• With two accounts signed in, click each account's notification and confirm the app opens on that account.
• With the window minimized, click a notification and confirm it restores.
• yarn electron-mocha --require .babel-register.js electron/src/window/activatePrimaryWindow.test.main.ts --no-sandbox