Add matrix module

First off, I would like to thank all of you for working on this project that allows beginners like myself to live inside emacs

**Describe the feature**
It would be great if doom had a module that set up and configured a matrix client, similar to how our `irc` module works already. Matrix is similar to discord in that it supports images and other stylistic abilites that irc lacks.
As far as I can tell, the prefered package to make emacs a matrix client is: `https://github.com/alphapapa/matrix-client.el`. The github repository also contains a shell script to isolate the matrix client from the rest of emacs, much like our `everywhere` or capture scripts.
If we were to add this modules, we would *need* to create some evil support; this repo lacks any form of evil-like bindings. We may also want to write some kind of integration for some evil support; this repo lacks any form of evil-like bindings. We may also want to write some kind of integration for [pantalaimon](https://github.com/matrix-org/pantalaimon), so that we could get end-to-end encryption

**System information**
https://pastebin.com/tUbHEB7g