[FEATURE] webhook request for dedicated channel type for Matrix

[tgurr]

Is your feature request related to a problem? Please describe.
It would be nice if a webhook channel type / template for the Matrix protocol could be added similiar to the already exising ones like Chime and Slack.

Describe the solution you'd like
Have Matrix as a Channel type available in the dropdown for easily configuring notifications on /app/notifications-dashboards#/create-channel

Describe alternatives you've considered
It can be done via the Custom webhook but in this case you might be missing some additional features like sending the messages as m.notice instead of m.text and nice input fields for the server, room, access token and message type would be very much welcomed (see Gitea screenshot posted below).

Additional context
Details on the official documentation: https://matrix.org/docs/guides/client-server-api#sending-messages

curl -XPOST -d '{"msgtype":"m.text", "body":"hello"}' "https://localhost:8448/_matrix/client/r0/rooms/%21asfLdzLnOdGRkdPZWu:localhost/send/m.room.message?access_token=YOUR_ACCESS_TOKEN"

An application that has added Matrix as a dedicated selectable Webhook is for example Gitea:
go-gitea/gitea@828a27f
go-gitea/gitea@bf60146

[kavilla]

Hello @tgurr,

Thank you for opening! Seems like a great idea!

Will re-route to Notifications plugin for follow-up but might require @opensearch-project/opensearch-ux to weigh in as well.