Implement push notification toggle in device detail

[germain-gg]

Implements the UI side of matrix-org/matrix-spec-proposals#3881
Fixes https://element-io.atlassian.net/browse/PSG-708

Acceptance criterias:

• Pushers are loaded with device list GET /_matrix/client/v3/pushers
• For devices with a related pusher, the push notification toggle is displayed in the session overview screen
• For devices without a related pusher, the push notifications section is not displayed
• Toggling the toggle sets the enabled property on the Pusher using POST /_matrix/client/v3/pushers/set
• any pusher without an enabled field should be treated as if enabled is false
• When there is no server support for setting is_disabled (see /versions response), the toggle should be disabled

Checklist

• Tests written for new code (and old code if feasible)
• Linter and other CI checks pass
• Sign-off given on the changes (see CONTRIBUTING.md)

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Here's what your changelog entry will look like:

✨ Features

• Implement push notification toggle in device detail (#9308).

[turt2live]

generally this seems fine, though the quality gate wants more tests

[turt2live]

Suggested change

	function getPusherForDevice(device: DeviceWithVerification): IPusher | null {
	return pushers.find(pusher => pusher[PUSHER_DEVICE_ID.name] === device.device_id);
	}
	const getPusherForDevice = (device: DeviceWithVerification): IPusher | null => {
	return pushers.find(pusher => pusher[PUSHER_DEVICE_ID.name] === device.device_id);
	};

I'm paranoid about scope changing randomly on us

[germain-gg]

I'm not sure I understand the rationale behind this change.
This function, overall declared will be scoped to the function it's declared in. Using const will scope it to the block it's declared in...
It's the whole concept of closures and sounds more like a stylistic preference