Fix notifications on all services

[SpecialAro]

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Description of Change

Change notification class to extend window.Notification.

Motivation and Context

Several users are reporting that notifications don't work on several services (noticed that icon was not being shown properly)
Maybe fixes #1105
Fixes #1751
Fixes #1747
Fixes #896
Fixes #1719
Fixes #1652

Steps to fix this PR:

• Fix the onClick function (not working since ever....) to properly open Ferdium (if closed), open the service, and go to the corresponding message on a service (new feature). (I was not able to implement this last logic... it's rather complex. Leaving for the future).
• For some reason, this new approach is spawning two notifications (I think that the first one is from window.Notification natively and that the other one is our class Notification). Nevertheless, clicking on the latest notification closes all notifications. Need help fixing this (@vraravam if you can take a look at this please) - or should we merge this PR with a "Known issue" for this?

Checklist

• My pull request is properly named
• The changes respect the code style of the project (pnpm prepare-code)
• pnpm test passes
• I tested/previewed my changes locally

Release Notes

Fixed several issues with notifications (double notifications, no icons on notification, content showing when private).
Added feature to open Ferdium and go to the specific service after clicking the notification.

[SpecialAro]

Self-reminder: This PR should also address the issue here (#1751) that was introduced by the extend window.Notifications