Notifications: add popup window for a call notification with join/decline buttons

[ShGKme]

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Is your feature request related to a problem? Please describe.

In contrast to a text message, a call notification often needs an immediate reaction to join a call.

Describe the solution you'd like

Add a pop-up window with a call notification with two buttons:

• "Join" - opens the talk window, opens the chat, joins the call
• "Decline" - closes the popup

Describe alternatives you've considered

Use native notifications. Make a call native notification always shown and add buttons to the notification. It is definitely possible on Windows, but I'm not sure it is possible on MacOS and all the Linux desktop environments.

Additional context

We have it on both Android and iOS mobile clients. See also: