Port Riot-iOS to MacOS

An attempt to port Riot on Mac has been attempted using Marzipan (https://pspdfkit.com/blog/2018/porting-ios-apps-to-mac-marzipan-iosmac-uikit-appkit/).

Here is the current conclusion:

```
Yan Minari 🚁: well, this goes beyond my (lack of) skills. if anyone wants to continue from where I left, you need to:
- prevent riot from using PushKit.framework, Photos.framework, and MediaPlayer.framework;
- prevent riot from using WebRTC framework (because it uses OpenGLES.framework and I don't think it would be quick to prevent it from using that)
- prevent JitsiMeet.framework from using AssetsLibrary.framework/
- prevent matrixSDK from using CallKit.framework and possibly avoid more frameworks
it also seems like marzipan don't like VMs too much (maybe due to lack of graphics acceleration), so I would do this on a second mac (because it requires disabling SIP and setting a boot flag)
```
(https://matrix.to/#/!tDRGDwZwQnlkowsjsm:matrix.org/$1537951534581215VNMHP:matrix.org)