Add Matrix as notification provider

[rhizoet]

Is it possible to add Matrix as a notification provider?

Matrix is now a protocol that is used very much and often. There are certainly many who would like to receive notifications there.

As example I have here a link from uptime-kuma, who have included it: https://github.com/louislam/uptime-kuma/blob/master/server/notification-providers/matrix.js