Create Android build

[tcpipuk]

This seems like it'd be an incredible text editor on mobile devices, especially the game aesthetic and effects.

Godot Engine has documentation (including a sample Android project) on how to build an Android project:
https://docs.godotengine.org/en/stable/tutorials/platform/android/android_library.html

Unfortunately I only have a tiny amount of experience developing for Android, so raising an issue here in the hope someone else finds this before I have time to study it!