Create CLI Tool (or similar)

[ephemer]

We need a way of setting up new UIKit projects for Android, with an easy way of building and maintaining the app for both Android and Mac.

Preferably we'd do this in Xcode, because we expect the cross-platform usability to be based around iOS-Android.

Before we do this, we should investigate:

• Whether it's possible to build entirely in Xcode (by using the mac android toolchain)
• If not, whether it's interesting to manage our build scripts from Xcode anyway (calling out to SwiftPM)
• How other open source projects deal with this issue (e.g. React Native and Create React App)