Font-awesome: Icon request: Matrix.org

[heitorPB]

What can it be used for?

Matrix is _An open network for secure, decentralized communication_. It is growing quite fast and has a lot of potential.

There are icons for Telegram (fa-telegram), Whatsapp (fa-whatsapp), Facebook Messenger (fa-facebook-messenger). Matrix needs one.

Example image (optional)

https://github.com/vector-im/logos/blob/master/matrix/matrix-favicon.png
https://github.com/vector-im/logos/blob/master/matrix/matrix-logo.png
https://github.com/vector-im/logos/tree/master/matrix

Icon request checklist

• [x] This is a single icon or matched pair (Ex: lock / unlock)
• [x] The title starts with "Icon request: " and is followed by the requested icon name (Ex: Icon request: magical-unicorn)
• [x] I have searched for existing issues and to the best of my knowledge this is not a duplicate
• [x] I have included at least one example image if it could be helpful (optional)
• [x] The request is for a concrete object (it's harder to make an icon to represent happiness, it's easier to make a smiley face. ☺)

[AnsgarSchmidt]

https://forkawesome.github.io/Fork-Awesome/icon/matrix-org/

[yeldiRium]

There is already a public domain svg, maybe that helps:
https://en.wikipedia.org/wiki/File:Matrix_icon.svg