Implement MSC3987: Push actions clean-up

[giomfo]

Steps to reproduce

Following MSC3987: Push actions clean-up, some recent clients mute a room by adding a new push rule with an empty list of actions

Outcome

This push rule seems ignored in Element-Web, the room is not displayed as muted room.

Element-Web SDK must support empty list of actions in push rules. This empty list must be considered as a "Don't notify" action

Note: this has been fixed on Element-iOS and Element-Android

Operating system

No response

Browser information

No response

URL for webapp

No response

Application version

Element version: 1.11.34

Homeserver

No response

Will you send logs?

No