ssb-keys-neon build fails on arm64

[black-puppydog]

This is just to track progress on this.
Out of the box, my build fails with a missing prebuild or some such.

I got it to compile by updating the 7.2.2 branch in my fork to include the various fixes andre made in the meantime, and then building on the pi to produce prebuilds.

@staltz how did you make all the prebuilds? were those generated by the build system or sth?

However, when trying to launch patchwork (after it built fine with npm ci) it now fails with a missing symbol error.
This is a known issue... well... hurdle. it's not a bug per se, but just a complicated build setup what with electron-builder and all:
neon-bindings/neon#581

So that's the state at the moment, and I'll continue with this later-on. The patch changing the reference for ssb-keys-neon to my fork is here: https://github.com/ssbc/patchwork/tree/neon-arm64