Linux x86_64 reproducible builds

[sneurlax]

Android might be feasible and I am checking the other platforms but we should only expect success for Linux and Android

I am updating build_app.sh to add a guix option and I am also updating the stack_releases scripts to make it easier to use this

[sneurlax]

Closes #6

IF the supported platforms are enough AND we can't figure out the rest of the platforms. Maybe guix will work in WSL2 for Windows builds and maybe if not guix then nix or something like that can work for macOS and/or iOS (I have doubts about the feasibility for iOS...)

[sneurlax]

cs_monero linux guix proof of concept pushed to https://github.com/cypherstack/cs_monero/compare/feat/guix ... but guix won't be suitable for macos and ios and there, nix will have to be used

nix is compatible w linux

first I am just seeing if nix can prove reproducibility for cs_monero

if that works then stack wallet may see a feat/nix instead of a feat/guix and this will just be an example

[sneurlax]

got nix working on linux and the rest of the platforms san win but just for flutter, not for stack wallet. TODO