Add support for event notifications over the Matrix protocol

What does this MR do and why?

Based on the #22996 (closed), this MR introduce new integration called Matrix, that is behaving similar to other BaseChatNotification.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

1. Checkout the branch
2. Create a new account on https://matrix.org/try-matrix/, e.g. https://app.element.io/
3. Setup the new integration using the roomId and user's access_token
4. Verify that everything works as expected 🎉

note: to find room_id and access_token, visit the room/user, and go to Settings/Advanced

Related to #22996 (closed)