ci: simplify nix hash updates

[gigamonster256]

exposes the platform specific node_module derivations at the flake level so that any builder can calculate any host platform hash

allows 1 builder to update all 4 supported platform hashes - turning 5 jobs and 4 artifacts into 1 job

NOTE: i had opus make the changes to the workflow, I'm not super familiar with actions

manually verified that all 4 current hashes match up with the new exposed package hashes

supersedes #8985