ARM version of package-builder

[IntinteDAO]

This isn't really a Package Request, but.
Thanks to udocker, we can run containers on any Android device—they don't always work correctly, but in my opinion, the lack of an ARM64 version of the ghcr.io/termux/package-builder:latest image makes building applications on Termux feel worse.

The question is, can we prepare the ghcr.io/termux/package-builder:latest image for ARM64 so that Termux users can build applications on their devices, but in a secure sandbox?

[robertkirkman]

I plan to implement this, but the blocker for me is:

• deblobbify, replacing the system folder with several other components termux-docker#72

I will implement all other boilerplate for it after that PR is merged.